Juanita L Merchant

Interests

Research

GI physiology Gastrointestinal cancersTranscriptional control mechanismsMouse models of GI physiology and cancerHelicobacter pylori and gastric cancer

Teaching

GI physiology Gastrointestinal cancersTranscriptional control mechanismsMouse models of GI physiology and cancerHelicobacter pylori and gastric cancer

Courses

Scholarly Contributions

Books

• Merchant, J. (2016). Recapitulating human gastric cancer pathogenesis: Experimental models of gastric cancer.
• Merchant, J. (2012). Physiology of the Gastrointestinal Tract.
• Merchant, J. (2006). Physiology of the Gastrointestinal Tract.

Chapters

• Merchant, J. (2018). Transcription and Epigenetic Regulation. In Physiology of the Gastrointestinal Tract: Sixth Edition.
• Merchant, J. (2010). Hedgehog signaling in gastric physiology and cancer. In Progress in Molecular Biology and Translational Science.
• Merchant, J. (2009). Atrophy and altered mesenchymal-epithelial signaling preceding gastric cancer. In The Biology of Gastric Cancers.
• Merchant, J. (2005). 4 role of p53 and ZBP-89 in hepatocellular carcinoma. In Handbook of Immunohistochemistry and in Situ Hybridization of Human Carcinomas.

Journals/Publications

• Arshad, J., Rao, A., Repp, M. L., Rao, R., Wu, C., & Merchant, J. L. (2024). Myeloid-Derived Suppressor Cells: Therapeutic Target for Gastrointestinal Cancers. International Journal of Molecular Sciences, 25(5), 2985. doi:10.3390/ijms25052985
• Duan, S., Sawyer, T. W., Witten, B. L., Song, H., Else, T., & Merchant, J. L. (2024). Spatial profiling reveals tissue-specific neuro-immune interactions in gastroenteropancreatic neuroendocrine tumors. Journal of Pathology, 262(Issue 3). doi:10.1002/path.6241
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  Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are heterogeneous malignancies that arise from complex cellular interactions within the tissue microenvironment. Here, we sought to decipher tumor-derived signals from the surrounding microenvironment by applying digital spatial profiling (DSP) to hormone-secreting and non-functional GEP-NETs. By combining this approach with in vitro studies of human-derived organoids, we demonstrated the convergence of cell autonomous immune and pro-inflammatory proteins that suggests their role in neuroendocrine differentiation and tumorigenesis. DSP was used to evaluate the expression of 40 neural- and immune-related proteins in surgically resected duodenal and pancreatic NETs (n = 20) primarily consisting of gastrinomas (18/20). A total of 279 regions of interest were examined between tumors, adjacent normal and abnormal-appearing epithelium, and the surrounding stroma. The results were stratified by tissue type and multiple endocrine neoplasia I (MEN1) status, whereas protein expression was validated by immunohistochemistry (IHC). A tumor immune cell autonomous inflammatory signature was further evaluated by IHC and RNAscope, while functional pro-inflammatory signaling was confirmed using patient-derived duodenal organoids. Gastrin-secreting and non-functional pancreatic NETs showed a higher abundance of immune cell markers and immune infiltrate compared with duodenal gastrinomas. Compared with non-MEN1 tumors, MEN1 gastrinomas and preneoplastic lesions showed strong immune exclusion and upregulated expression of neuropathological proteins. Despite a paucity of immune cells, duodenal gastrinomas expressed the pro-inflammatory and pro-neural factor IL-17B. Treatment of human duodenal organoids with IL-17B activated NF-κB and STAT3 signaling and induced the expression of neuroendocrine markers. In conclusion, multiplexed spatial protein analysis identified tissue-specific neuro-immune signatures in GEP-NETs. Duodenal gastrinomas are characterized by an immunologically cold microenvironment that permits cellular reprogramming and neoplastic transformation of the preneoplastic epithelium. Moreover, duodenal gastrinomas cell autonomously express immune and pro-inflammatory factors, including tumor-derived IL-17B, that stimulate the neuroendocrine phenotype. © 2024 The Pathological Society of Great Britain and Ireland.
• Duan, S., Sontz, R. A., Deymier, M., & Merchant, J. L. (2024). Abstract 3586: A Hedgehog-dependent signaling axis drives neural plasticity and oncogenic reprogramming in gastroenteropancreatic neuroendocrine tumors. Cancer Research, 84(6_Supplement), 3586-3586. doi:10.1158/1538-7445.am2024-3586
• Knapp, T., Lima, N., Daigle, N., Duan, S., Merchant, J. L., & Sawyer, T. W. (2024). Combined flat-field and frequency filter approach to correcting artifacts of multichannel two-photon microscopy. Journal of Biomedical Optics, 29(01). doi:10.1117/1.jbo.29.1.016007
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  SignificanceMultiphoton microscopy (MPM) is a useful biomedical imaging tool for its ability to probe labeled and unlabeled depth-resolved tissue biomarkers at high resolution. Automated MPM tile scanning allows for whole-slide image acquisition but can suffer from tile-stitching artifacts that prevent accurate quantitative data analysis.AimWe have investigated postprocessing artifact correction methods using ImageJ macros and custom Python code. Quantitative and qualitative comparisons of these methods were made using whole-slide MPM autofluorescence and second-harmonic generation images of human duodenal tissue.ApproachImage quality after artifact removal is assessed by evaluating the processed image and its unprocessed counterpart using the root mean square error, structural similarity index, and image histogram measurements.ResultsConsideration of both quantitative and qualitative results suggest that a combination of a custom flat-field-based correction and frequency filtering processing step provide improved artifact correction when compared with each method used independently to correct for tiling artifacts of tile-scan MPM images.ConclusionsWhile some image artifacts remain with these methods, further optimization of these processing steps may result in computational-efficient methods for removing these artifacts that are ubiquitous in large-scale MPM imaging. Removal of these artifacts with retention of the original image information would facilitate the use of this imaging modality in both research and clinical settings, where it is highly useful in collecting detailed morphologic and optical properties of tissue.
• Bailey, K. S., Brown, H. E., Lekic, V., Pradeep, K., Merchant, J. L., & Harris, R. B. (2023). Helicobacter pylori treatment knowledge, access and barriers: A cross-sectional study. Helicobacter, 28(Issue 2). doi:10.1111/hel.12954
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  Background: Helicobacter pylori (Hp) is among the most common bacterial infections in the world and one of the most common infectious agents linked to malignancy, gastric cancer (GC). Within the US there is high disparity in the rates of Hp infection and associated diseases. Hp infection is treatable, and knowledge may influence screening and treatment seeking behaviors. Materials and Methods: In this cross-sectional study of 1042 respondents recruited from the Online Amazon MTurk platform, we sought to assess baseline knowledge of Hp and to gain insight into barriers related to Hp care. Results: Just over half (52.3%) reported some prior knowledge of Hp with 11.7% (n = 122) reporting being treated for Hp themselves and 21.4% reporting family members diagnosed with Hp. Of respondents reporting prior treatment, 95 (78%) reported GI upset and 27 (21%) reported not completing medications. Specific to Hp and GC, 70% indicated that a belief that the treatment was worse than the symptoms would affect their willingness to seek care, while 81% indicated knowing Hp can cause GC would affect their treatment decisions and knowing their gastric symptoms were caused by Hp would affect their willingness to receive care. Conclusions: Knowledge of Hp in this US sample of online respondents is low and self-reported difficulties with treatment compliance is high. Increasing awareness of this infection and addressing the challenges to treatment compliance could potentially reduce rates of Hp antibiotic resistance and progression to GC or other complications of Hp infection.
• Chopp, L. B., Zhu, X., Gao, Y., Nie, J., Singh, J., Kumar, P., Young, K. Z., Patel, S., Li, C., Balmaceno-Criss, M., Vacchio, M. S., Wang, M. M., Livak, F., Merchant, J. L., Wang, L., Kelly, M. C., Zhu, J., & Bosselut, R. (2023). Zfp281 and Zfp148 control CD4 ⁺ T cell thymic development and T _H 2 functions. Science Immunology, 8(89). doi:10.1126/sciimmunol.adi9066
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  How CD4+ lineage gene expression is initiated in differentiating thymocytes remains poorly understood. Here, we show that the paralog transcription factors Zfp281 and Zfp148 control both this process and cytokine expression by T helper cell type 2 (TH2) effector cells. Genetic, single-cell, and spatial transcriptomic analyses showed that these factors promote the intrathymic CD4+ T cell differentiation of class II major histocompatibility complex (MHC II)-restricted thymocytes, including expression of the CD4+ lineage-committing factor Thpok. In peripheral T cells, Zfp281 and Zfp148 promoted chromatin opening at and expression of TH2 cytokine genes but not of the TH2 lineage-determining transcription factor Gata3. We found that Zfp281 interacts with Gata3 and is recruited to Gata3 genomic binding sites at loci encoding Thpok and TH2 cytokines. Thus, Zfp148 and Zfp281 collaborate with Gata3 to promote CD4+ T cell development and TH2 cell responses.
• Daigle, N., Duan, S., Song, H., Lima, N., Sontz, R., Merchant, J. L., & Sawyer, T. W. (2023). Wide field-of-view fluorescence imaging for organ-level lineage tracing of rare intestinal stem cell populations. Journal of Biomedical Optics, 28(09). doi:10.1117/1.jbo.28.9.096004
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  Lineage tracing using fluorescent reporters is a common tool for monitoring the expression of genes and transcription factors in stem cell populations and their progeny. The zinc-binding protein 89 (ZBP-89/Zfp148 mouse gene) is a transcription factor that plays a role in gastrointestinal (GI) stem cell maintenance and cellular differentiation and has been linked to the progression of colon cancer. While lineage tracing is a useful tool, it is commonly performed with high-magnification microscopy on a small field of view within tissue sections, thereby limiting the ability to resolve reporter expression at the organ level. Furthermore, this technique requires extensive tissue processing, which is time consuming and requires euthanizing the animal. Further knowledge could be elucidated by measuring the expression of fluorescent reporters across entire organs with minimal tissue processing.We present the application of wide-field fluorescence imaging for whole-organ lineage tracing of an inducible Zfp148-tdTomato-expressing transgenic mouse line to assess the expression of ZBP-89/Zfp148 in the GI tract.We measured tdTomato fluorescence in ex vivo organs at time points between 24 h and 6 months post-induction. Fluctuations in tdTomato expression were validated by fluorescence microscopy of tissue sections.Quantification of the wide field-of-view images showed a statistically significant increase in fluorescent signal across the GI tract between transgenic mice and littermate controls. The results also showed a gradient of decreasing reporter expression from proximal to distal intestine, suggesting a higher abundance of ZBP-89 expressing stem cells, or higher expression of ZBP-89 within the stem cells, in the proximal intestine.We demonstrate that wide-field fluorescence imaging is a valuable tool for monitoring whole-organ expression of fluorescent reporters. This technique could potentially be applied in vivo for longitudinal assessment of a single animal, further enhancing our ability to resolve rare stem cell lineages spatially and temporally.
• Ding, L., Sheriff, S., Sontz, R. A., & Merchant, J. L. (2023). Schlafen4+-MDSC in Helicobacter-induced gastric metaplasia reveals role for GTPases. Frontiers in Immunology, 14(Issue). doi:10.3389/fimmu.2023.1139391
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  Introduction: MDSCs express SCHLAFEN 4 (SLFN4) in Helicobacter-infected stomachs coincident with spasmolytic polypeptide-expressing metaplasia (SPEM), a precursor of gastric cancer. We aimed to characterize SLFN4+ cell identity and the role of Slfn4 in these cells. Methods: Single-cell RNA sequencing was performed on immune cells sorted from PBMCs and stomachs prepared from uninfected and 6-month H. felis-infected mice. Knockdown of Slfn4 by siRNA or PDE5/6 inhibition by sildenafil were performed in vitro. Intracellular ATP/GTP levels and GTPase activity of immunoprecipitated Slfn4 complexes were measured using the GTPase-Glo assay kit. The intracellular level of ROS was quantified by the DCF-DA fluorescent staining, and apoptosis was determined by cleaved Caspase-3 and Annexin V expression. Gli1CreERT2 x Slfn4fl/fl mice were generated and infected with H. felis. Sildenafil was administered twice over 2 weeks by gavaging H. felis infected mice ~4 months after inoculation once SPEM had developed. Results: Slfn4 was highly induced in both monocytic and granulocytic MDSCs from infected stomachs. Both Slfn4+-MDSC populations exhibited strong transcriptional signatures for type-I interferon responsive GTPases and exhibited T cell suppressor function. SLFN4-containing protein complexes immunoprecipitated from myeloid cell cultures treated with IFNa exhibited GTPase activity. Knocking down Slfn4 or PDE5/6 inhibition with sildenafil blocked IFNa induction of GTP, SLFN4 and NOS2. Moreover, IFNa induction of Slfn+-MDSC function was inhibited by inducing their reactive oxygen species (ROS) production and apoptosis through protein kinase G activation. Accordingly, in vivo disruption of Slfn4 in Gli1CreERT2 x Slfn4fl/fl mice or pharmacologic inhibition by sildenafil after Helicobacter infection also suppressed SLFN4 and NOS2, reversed T cell suppression and mitigated SPEM development. Conclusion: Taken together, SLFN4 regulates the activity of the GTPase pathway in MDSCs and precludes these cells from succumbing to the massive ROS generation when they acquire MDSC function.
• Duan, S., Sheriff, S., Elvis-Offiah, U. B., Witten, B. L., Sawyer, T. W., Sundaresan, S., Cierpicki, T., Grembecka, J., & Merchant, J. L. (2023). Clinically Defined Mutations in MEN1 Alter Its Tumor-suppressive Function Through Increased Menin Turnover. Cancer Research Communications, 3(7), 1318-1334. doi:10.1158/2767-9764.crc-22-0522
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  R516fs and E235K mutations exhibit reduced protein stability and shortened half-lives compared with wild-type (WT) menin. A, Western blot analysis of MEFΔMen1 whole-cell extracts following overexpression of wild-type menin in the presence of the protein synthesis inhibitor cycloheximide (CHX, 10 μmol/L) alone or pretreated with the proteosome inhibitor MG132 (10 μmol/L). B, Normalized FLAG band signal intensity plotted as a function of time in the presence of CHX with and without MG132 pretreatment. Overexpression of the R516fs (C–D), E235K(E, F), and A541T (G, H) menin proteins with normalized FLAG band signal intensity plotted as a function of time in the presence of CHX alone or in combination with MG132 pretreatment. n = 3 experimental replicates, mean ± SEM. *, P < 0.05; ***, P < 0.01; ****, P < 0.0001 by two-way ANOVA.
• Elvis‐Offiah, U. B., Duan, S., & Merchant, J. L. (2023). MENIN‐mediated regulation of gastrin gene expression and its role in gastrinoma development. The FASEB Journal, 37(5). doi:10.1096/fj.202201809rr
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  The Multiple Endocrine Neoplasia I (MEN1) locus encodes the protein MENIN, which functions as a tumor suppressor protein in neuroendocrine tissues. Gastrinomas are neuroendocrine neoplasms that overproduce the hormone gastrin and can arise sporadically or as part of the MEN1 syndrome, in which mutations in the MEN1 gene lead to loss or inactivation of MENIN protein. Gastrin is a peptide hormone that is primarily synthesized in the gastric antrum and stimulates the secretion of histamine from enterochromaffin-like (ECL) cells and subsequently acid from parietal cells in the gastric corpus. In addition, gastrin exerts a mitogenic function primarily on ECL cells and progenitor cells in the gastric isthmus. Current studies seek to understand how MEN1 mutations generate a mutant MENIN protein that abrogates its tumor suppressor function. Mutations in the MEN1 gene are broadly distributed throughout its nine protein-coding exons, making it difficult to correlate protein structure with its function. Although disruption of the Men1 locus in mice causes functional neuroendocrine tumors in the pituitary and pancreas, gastrinomas do not develop in these transgenic animal models. Prior studies of human gastrinomas suggest that tissue-specific microenvironmental cues in the submucosal foregut may contribute to tumorigenesis by reprogramming of epithelial cells toward the neuroendocrine phenotype. Accordingly, recent studies suggest that neural crest-derived cells are also sensitive to reprogramming when MEN1 is deleted or mutated. Thus, the goal of this report is to review our current understanding of how MENIN modulates gastrin gene expression while highlighting its role in the prevention/suppression of neuroendocrine cell transformation.
• Hibdon, E. S., Keeley, T. M., Merchant, J. L., & Samuelson, L. C. (2023). The bHLH transcription factor ASCL1 promotes differentiation of endocrine cells in the stomach and is regulated by Notch signaling. American Journal of Physiology-Gastrointestinal and Liver Physiology, 325(5), G458-G470. doi:10.1152/ajpgi.00043.2023
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  Notch signaling regulates gastrointestinal stem cell proliferation and differentiation yet Notch-regulated transcriptional effectors of gastric epithelial cell differentiation are poorly understood. Here we tested the role of the bHLH transcription factor Achaete-Scute homolog 1 (ASCL1) in gastric epithelial cell differentiation, and its regulation by Notch. Newborn Ascl1 null mice showed a loss of expression of markers of neurogenin-3-dependent enteroendocrine cells, with normal expression of enterochromaffin-like cells, mucous cells, chief cells, and parietal cells. In adult mice, Ascl1 gene expression was observed in the stomach, but not the intestine, with higher expression in antral than corpus epithelium. Lineage tracing in Ascl1-CreERT2; Rosa26-LSL-tdTomato mice revealed single, scattered ASCL1+ cells in the gastric epithelium, demonstrating expression in antral gastrin- and serotonin-producing endocrine cells. ASCL1-expressing endocrine cells persisted for several weeks posttamoxifen labeling with a half-life of approximately 2 months. Lineage tracing in Gastrin-CreERT2 mice demonstrated a similar lifespan for gastrin-producing cells, confirming that gastric endocrine cells are long-lived. Finally, treatment of Ascl1-CreERT2; Rosa26-LSL-tdTomato mice with the pan-Notch inhibitor dibenzazepine increased the number of lineage-labeled cells in the gastric antrum, suggesting that Notch signaling normally inhibits Ascl1 expression. Notch regulation of Ascl1 was also demonstrated in a genetic mouse model of Notch activation, as well as Notch-manipulated antral organoid cultures, thus suggesting that ASCL1 is a key downstream Notch pathway effector promoting endocrine cell differentiation in the gastric epithelium.NEW & NOTEWORTHY Although Notch signaling is known to regulate cellular differentiation in the stomach, downstream effectors are poorly described. Here we demonstrate that the bHLH transcription factor ASCL1 is expressed in endocrine cells in the stomach and is required for formation of neurogenin-3-dependent enteroendocrine cells but not enterochromaffin-like cells. We also demonstrate that Ascl1 expression is inhibited by Notch signaling, suggesting that ASCL1 is a Notch-regulated transcriptional effector directing enteroendocrine cell fate in the mouse stomach.
• Loi, S., Settleman, J., Joyce, J. A., Pramesh, C. S., Bernards, R., Fan, J., Merchant, J. L., Moslehi, J., & Sellers, W. R. (2023). The next big questions in cancer research. Cell, 186(Issue 8). doi:10.1016/j.cell.2023.01.037
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  Our understanding of tumorigenesis and cancer progression as well as clinical therapies for different cancer types have evolved dramatically in recent years. However, even with this progress, there are big challenges for scientists and oncologists to tackle, ranging from unpacking the molecular and cellular mechanisms involved to therapeutics and biomarker development to quality of life in the aftermath of therapy. In this article, we asked researchers to comment on the questions that they think are important to address in the coming years.
• Merchant, J. L. (2023). DDS Perspective: The Joy of Discovery and the Art of Mentoring. Digestive Diseases and Sciences, 68(Issue 1). doi:10.1007/s10620-022-07726-y
• Merchant, J. L. (2023). DDS Profile: Juanita L. Merchant, MD, PhD. Digestive Diseases and Sciences, 68(Issue 1). doi:10.1007/s10620-022-07725-z
• Merchant, J. L., Song, H. L., & Stoffel, E. M. (2023). Evidence for diet-gene interaction in early-onset colorectal cancer.. Journal of Clinical Oncology, 41(4_suppl), 182-182. doi:10.1200/jco.2023.41.4_suppl.182
• Song, H., Sontz, R. A., Vance, M. J., Morris, J. M., Sheriff, S., Zhu, S., Duan, S., Zeng, J., Koeppe, E., Pandey, R., Thorne, C. A., Stoffel, E. M., & Merchant, J. L. (2023). High-fat diet plus HNF1A variant promotes polyps by activating β-catenin in early-onset colorectal cancer. JCI Insight, 8(Issue 13). doi:10.1172/jci.insight.167163
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  The incidence of early-onset colorectal cancer (EO-CRC) is rising and is poorly understood. Lifestyle factors and altered genetic background possibly contribute. Here, we performed targeted exon sequencing of archived leukocyte DNA from 158 EO-CRC participants, which identified a missense mutation at p.A98V within the proximal DNA binding domain of Hepatic Nuclear Factor 1 α (HNF1AA98V, rs1800574). The HNF1AA98V exhibited reduced DNA binding. To test function, the HNF1A variant was introduced into the mouse genome by CRISPR/Cas9, and the mice were placed on either a high-fat diet (HFD) or high-sugar diet (HSD). Only 1% of the HNF1A mutant mice developed polyps on normal chow; however, 19% and 3% developed polyps on the HFD and HSD, respectively. RNA-Seq revealed an increase in metabolic, immune, lipid biogenesis genes, and Wnt/β-catenin signaling components in the HNF1A mutant relative to the WT mice. Mouse polyps and colon cancers from participants carrying the HNF1AA98V variant exhibited reduced CDX2 and elevated β-catenin proteins. We further demonstrated decreased occupancy of HNF1AA98V at the Cdx2 locus and reduced Cdx2 promoter activity compared with WT HNF1A. Collectively, our study shows that the HNF1AA98V variant plus a HFD promotes the formation of colonic polyps by activating β-catenin via decreasing Cdx2 expression.
• Abrams, J., Camilleri, M., Merchant, J., Rustgi, A. K., & Yan, K. (2022). Presentation of the Julius M. Friedenwald Medal to Timothy C. Wang, MD, AGAF. Gastroenterology, 162(Issue 7). doi:10.1053/j.gastro.2022.03.021
• Dagur, P., Feng, J., McCoy, J. P., Merchant, J. L., Sei, Y., Wank, S. A., & Zhao, X. (2022). Tissue and cell specific properties of enterochromaffin cells affect the fate of tumorigenesis toward non-endocrine adenocarcinoma of the small intestine. American Journal of Physiology-Gastrointestinal and Liver Physiology, 324(3), G177-G189. doi:10.1152/ajpgi.00205.2022
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  Small intestinal neuroendocrine tumors (SI-NETs) are serotonin-secreting well-differentiated neuroendocrine tumors of putative enterochromaffin (EC) cell origin. However, EC cell-derived tumorigenesis remains poorly understood. Here, we examined whether the gain of Myc and the loss of RB1 and Trp53 function in EC cells result in SI-NET using tryptophan hydroxylase 1 (TPH1) Cre-ERT2-driven RB1fl Trp53fl MycLSL (RPM) mice. TPH1-Cre-induced gain of Myc and loss of RB1 and Trp53 function resulted in endocrine or neuronal tumors in pancreas, lung, enteric neurons, and brain. Lineage tracing indicated that the cellular origin for these tumors was TPH1-expressing neuroendocrine, neuronal, or their precursor cells in these organs. However, despite that TPH1 is most highly expressed in EC cells of the small intestine, we observed no incidence of EC cell tumors. Instead, the tumor of epithelial cell origin in the intestine was exclusively nonendocrine adenocarcinoma, suggesting dedifferentiation of EC cells into intestinal stem cells (ISCs) as a cellular mechanism. Furthermore, ex vivo organoid studies indicated that loss of functions of Rb1 and Trp53 accelerated dedifferentiation of EC cells that were susceptible to apoptosis with expression of activated MycT58A, suggesting that the rare dedifferentiating cells escaping cell death went on to develop adenocarcinomas. Lineage tracing demonstrated that EC cells in the small intestine were short-lived compared with neuroendocrine or neuronal cells in other organs. In contrast, EC cell-derived ISCs were long-lasting and actively cycling and thus susceptible to transformation. These results suggest that tissue- and cell-specific properties of EC cells such as rapid cell turnover and homeostatic dedifferentiation, affect the fate and rate of tumorigenesis induced by genetic alterations and provide important insights into EC cell-derived tumorigenesis.NEW & NOTEWORTHY Small intestinal neuroendocrine tumors are of putative enterochromaffin (EC) cell origin and are the most common malignancy in the small intestine, followed by adenocarcinoma. However, the tumorigenesis of these tumor types remains poorly understood. The present lineage tracing studies showed that tissue- and cell-specific properties of EC cells such as rapid cell turnover and homeostatic dedifferentiation affect the fate and rate of tumorigenesis induced by genetic alterations toward a rare occurrence of adenocarcinoma.
• Ding, L., Chakrabarti, J., Sheriff, S., Li, Q., Thi Hong, H. N., Sontz, R. A., Mendoza, Z. E., Schreibeis, A., Helmrath, M. A., Zavros, Y., & Merchant, J. L. (2022). Toll-like Receptor 9 Pathway Mediates Schlafen+-MDSC Polarization During Helicobacter-induced Gastric Metaplasias. Gastroenterology, 163(Issue 2). doi:10.1053/j.gastro.2022.04.031
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  Background & Aims: A subset of myeloid-derived suppressor cells (MDSCs) that express murine Schlafen4 (SLFN4) or its human ortholog SLFN12L polarize in the Helicobacter-inflamed stomach coincident with intestinal or spasmolytic polypeptide-expressing metaplasia. We propose that individuals with a more robust response to damage-activated molecular patterns and increased Toll-like receptor 9 (TLR9) expression are predisposed to the neoplastic complications of Helicobacter infection. Methods: A mouse or human Transwell co-culture system composed of dendritic cells (DCs), 2-dimensional gastric epithelial monolayers, and Helicobacter were used to dissect the cellular source of interferon-α (IFNα) in the stomach by flow cytometry. Conditioned media from the co-cultures polarized primary myeloid cells. MDSC activity was determined by T-cell suppression assays. In human subjects with intestinal metaplasia or gastric cancer, the rs5743836 TLR9T>C variant was genotyped and linked to TLR9, IFNα, and SLFN12L expression by immunohistochemistry. Nuclear factor-κB binding to the TLR9 C allele was determined by electrophoretic mobility shift assays. Results: Helicobacter infection induced gastric epithelial and plasmacytoid DC expression of TLR9 and IFNα. Co-culturing primary mouse or human cells with DCs and Helicobacter induced TLR9, IFNα secretion, and SLFN+-MDSC polarization. Neutralizing IFNα in vivo mitigated Helicobacter-induced spasmolytic polypeptide-expressing metaplasia. The TLR9 minor C allele creates a nuclear factor-κB binding site associated with higher levels of TLR9, IFNα, and SLFN12L in Helicobacter-infected stomachs that correlated with a greater incidence of metaplasias and cancer. Conclusions: TLR9 plays an essential role in the production of IFNα and polarization of SLFN+ MDSCs on Helicobacter infection. Subjects carrying the rs5743836 TLR9 minor C allele are predisposed to neoplastic complications if chronically infected.
• Duan, S., Knapp, T. G., Merchant, J. L., & Sawyer, T. W. (2022). Quantitative characterization of duodenal gastrinoma autofluorescence using multiphoton microscopy. Lasers in Surgery and Medicine, 55(2), 208-225. doi:10.1002/lsm.23619
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  Abstract Background Duodenal gastrinomas (DGASTs) are neuroendocrine tumors that develop in the submucosa of the duodenum and produce the hormone gastrin. Surgical resection of DGASTs is complicated by the small size of these tumors and the tendency for them to develop diffusely in the duodenum. Endoscopic mucosal resection of DGASTs is an increasingly popular method for treating this disease due to its low complication rate but suffers from poor rates of pathologically negative margins. Multiphoton microscopy can capture high‐resolution images of biological tissue with contrast generated from endogenous fluorescence (autofluorescence [AF]) through two‐photon excited fluorescence (2PEF). Second harmonic generation is another popular method of generating image contrast with multiphoton microscopy (MPM) and is a light‐scattering phenomenon that occurs predominantly from structures such as collagen in biological samples. Some molecules that contribute to AF change in abundance from processes related to the cancer disease process (e.g., metabolic changes, oxidative stress, and angiogenesis). Study Design/Materials and Methods MPM was used to image 12 separate patient samples of formalin‐fixed and paraffin‐embedded duodenal gastrinoma slides with a second‐harmonic generation (SHG) channel and four 2PEF channels. The excitation and emission profiles of each 2PEF channel were tuned to capture signal dominated by distinct fluorophores with well‐characterized fluorescent spectra and known connections to the physiologic changes that arise in cancerous tissue. Results We found that there was a significant difference in the relative abundance of signal generated in the 2PEF channels for regions of DGASTs in comparison to the neighboring tissues of the duodenum. Data generated from texture feature extraction of the MPM images were used in linear discriminant analysis models to create classifiers for tumor versus all other tissue types before and after principal component analysis (PCA). PCA improved the classifier accuracy and reduced the number of features required to achieve maximum accuracy. The linear discriminant classifier after PCA distinguished between tumor and other tissue types with an accuracy of 90.6%−93.8%. Conclusions These results suggest that multiphoton microscopy 2PEF and SHG imaging is a promising label‐free method for discriminating between DGASTs and normal duodenal tissue which has implications for future applications of in vivo assessment of resection margins with endoscopic MPM.
• Duan, S., Merchant, J. L., & Rico, K. (2022). Gastrin: From Physiology to Gastrointestinal Malignancies.. Function (Oxford, England), 3(1), zqab062. doi:10.1093/function/zqab062
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  Abetted by widespread usage of acid-suppressing proton pump inhibitors (PPIs), the mitogenic actions of the peptide hormone gastrin are being revisited as a recurring theme in various gastrointestinal (GI) malignancies. While pathological gastrin levels are intricately linked to hyperplasia of enterochromaffin-like cells leading to carcinoid development, the signaling effects exerted by gastrin on distinct cell types of the gastric mucosa are more nuanced. Indeed, mounting evidence suggests dichotomous roles for gastrin in both promoting and suppressing tumorigenesis. Here, we review the major upstream mediators of gastrin gene regulation, including inflammation secondary to Helicobacter pylori infection and the use of PPIs. We further explore the molecular biology of gastrin in GI malignancies, with particular emphasis on the regulation of gastrin in neuroendocrine neoplasms. Finally, we highlight tissue-specific transcriptional targets as an avenue for targetable therapeutics.
• Duan, S., Sawyer, T. W., Sontz, R. A., Wieland, B. A., Diaz, A. F., & Merchant, J. L. (2022). GFAP-directed Inactivation of Men1 Exploits Glial Cell Plasticity in Favor of Neuroendocrine Reprogramming. Cellular and Molecular Gastroenterology and Hepatology, 14(Issue 5). doi:10.1016/j.jcmgh.2022.06.009
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  Background & Aims: Efforts to characterize the signaling mechanisms that underlie gastroenteropancreatic neoplasms (GEP-NENs) are precluded by a lack of comprehensive models that recapitulate pathogenesis. Investigation into a potential cell-of-origin for gastrin-secreting NENs revealed a non-cell autonomous role for loss of menin in neuroendocrine cell specification, resulting in an induction of gastrin in enteric glia. Here, we investigated the hypothesis that cell autonomous Men1 inactivation in glial fibrillary acidic protein (GFAP)-expressing cells induced neuroendocrine differentiation and tumorigenesis. Methods: Transgenic GFAPΔMen1 mice were generated by conditional GFAP-directed Men1 deletion in GFAP-expressing cells. Cre specificity was confirmed using a tdTomato reporter. GFAPΔMen1 mice were evaluated for GEP-NEN development and neuroendocrine cell hyperplasia. Small interfering RNA-mediated Men1 silencing in a rat enteric glial cell line was performed in parallel. Results: GFAPΔMen1 mice developed pancreatic NENs, in addition to pituitary prolactinomas that phenocopied the human MEN1 syndrome. GFAPΔMen1 mice exhibited gastric neuroendocrine hyperplasia that coincided with a significant loss of GFAP expression. Men1 deletion induced loss of glial-restricted progenitor lineage markers and an increase in neuroendocrine genes, suggesting a reprogramming of GFAP+ cells. Deleting Kif3a, a mediator of Hedgehog signaling, in GFAP-expressing cells attenuated neuroendocrine hyperplasia by restricting the neuroendocrine cell fate. Similar results in the pancreas were observed when Sox10 was used to delete Men1. Conclusions: GFAP-directed Men1 inactivation exploits glial cell plasticity in favor of neuroendocrine differentiation.
• Merchant, J. L. (2022). Moving Up a NOTCH: Defining the Stem Cell Niche in the Gastric Antrum. Cellular and molecular gastroenterology and hepatology, 13(1), 339-340.
• Merchant, J. L., & Zavros, Y. (2022). The immune microenvironment in gastric adenocarcinoma. Nature Reviews Gastroenterology & Hepatology. doi:10.1038/s41575-022-00591-0
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  Like most solid tumours, the microenvironment of epithelial-derived gastric adenocarcinoma (GAC) consists of a variety of stromal cell types, including fibroblasts, and neuronal, endothelial and immune cells. In this article, we review the role of the immune microenvironment in the progression of chronic inflammation to GAC, primarily the immune microenvironment driven by the gram-negative bacterial species Helicobacter pylori. The infection-driven nature of most GACs has renewed awareness of the immune microenvironment and its effect on tumour development and progression. About 75-90% of GACs are associated with prior H. pylori infection and 5-10% with Epstein-Barr virus infection. Although 50% of the world's population is infected with H. pylori, only 1-3% will progress to GAC, with progression the result of a combination of the H. pylori strain, host susceptibility and composition of the chronic inflammatory response. Other environmental risk factors include exposure to a high-salt diet and nitrates. Genetically, chromosome instability occurs in ~50% of GACs and 21% of GACs are microsatellite instability-high tumours. Here, we review the timeline and pathogenesis of the events triggered by H. pylori that can create an immunosuppressive microenvironment by modulating the host's innate and adaptive immune responses, and subsequently favour GAC development.
• Pond, K., Alkhimenok, O., Morris, J., Cabel, C. R., Alkhimenok, O., Chakrabarti, J., Varghese, R., Ellis, N. A., Cabel, C., Merchant, J. L., Ellis, N., Morris, J. M., Chakrabarti, J., Paek, A. L., Zavros, Y., Pond, K. W., Merchant, J., Thorne, C. A., Thorne, C., , Varghese, R. P., et al. (2022). Live-cell imaging in human colonic monolayers reveals ERK waves limit the stem cell compartment to maintain epithelial homeostasis. eLife, 11. doi:10.7554/elife.78837
• Slomka, B., Duan, S., Knapp, T. G., Lima, N., Sontz, R., Merchant, J. L., & Sawyer, T. W. (2022). Design, fabrication, and preclinical testing of a miniaturized, multispectral, chip-on-tip, imaging probe for intraluminal fluorescence imaging of the gastrointestinal tract. Frontiers in Photonics, 3(Issue). doi:10.3389/fphot.2022.1067651
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  Gastrointestinal cancers continue to account for a disproportionately large percentage of annual cancer deaths in the United States. Advancements in miniature imaging technology combined with a need for precise and thorough tumor detection in gastrointestinal cancer screenings fuel the demand for new, small-scale, and low-cost methods of localization and margin identification with improved accuracy. Here, we report the development of a miniaturized, chip-on-tip, multispectral, fluorescence imaging probe designed for compatibility with a gastroscope working channel with the aim of detecting cancerous lesions in point-of-care endoscopy of the gastrointestinal lumen. Preclinical testing has confirmed fluorescence sensitivity and supports that this miniature probe can locate structures of interest via detection of fluorescence emission from exogenous contrast agents. This work demonstrates the design and preliminary performance evaluation of a miniaturized, single-use, chip-on-tip fluorescence imaging system, capable of detecting multiplexed fluorophores, and devised for deployment via the accessory channel of a standard gastroscope.
• Chakrabarti, J., Koh, V., Steele, N., Hawkins, J., Ito, Y., Merchant, J. L., Wang, J., Helmrath, M. A., Ahmad, S. A., So, J. B., Yong, W. P., & Zavros, Y. (2021). Disruption of Her2-Induced PD-L1 Inhibits Tumor Cell Immune Evasion in Patient-Derived Gastric Cancer Organoids. Cancers, 13(24).
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  (1) Background: The expression of programmed death-ligand 1 (PD-L1), which interacts with programmed cell death protein 1 (PD-1) on cytotoxic T lymphocytes (CTLs), enables tumors to escape immunosurveillance. The PD-1/PD-L1 interaction results in the inhibition of CTL proliferation, and effector function, thus promoting tumor cell evasion from immunosurveillance and cancer persistence. Despite 40% of gastric cancer patients exhibiting PD-L1 expression, only a small subset of patients responds to immunotherapy. Human epidermal growth factor receptor2 (HER2) is one of the critical regulators of several solid tumors, including metastatic gastric cancer. Although half of PD-L1-positive gastric tumors co-express HER2, crosstalk between HER2 and PD-1/PD-L1 in gastric cancer remains undetermined. (2) Methods: Human gastric cancer organoids (huTGOs) were generated from biopsied or resected tissues and co-cultured with CTLs and myeloid-derived suppressor cells (MDSCs). Digital Spatial Profiling (DSP) was performed on FFPE tissue microarrays of numerous gastric cancer patients to examine the protein expression of immune markers. (3) Results: Knockdown of HER2 in PD-L1/HER2-positive huTGOs led to a concomitant decrease in PD-L1 expression. Similarly, in huTGOs/immune cell co-cultures, PD-L1 expression decreased in huTGOs and was correlated with an increase in CTL proliferation which enhanced huTGO death. Treatment with Nivolumab exhibited similar effects. However, a combinatorial treatment with Mubritinib and Nivolumab was unable to inhibit HER2 expression in co-cultures containing MDSCs. (4) Conclusions: Our study suggested that co-expression of HER2 and PD-L1 may contribute to tumor cell immune evasion. In addition, autologous organoid/immune cell co-cultures can be exploited to effectively screen responses to a combination of anti-HER2 and immunotherapy to tailor treatment for gastric cancer patients.
• Ding, L., Sontz, E. A., Saqui-Salces, M., & Merchant, J. L. (2021). Interleukin-1β Suppresses Gastrin via Primary Cilia and Induces Antral Hyperplasia. Cellular and molecular gastroenterology and hepatology, 11(5), 1251-1266.
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  Helicobacter pylori infection in humans typically begins with colonization of the gastric antrum. The initial Th1 response occasionally coincides with an increase in gastrin secretion. Subsequently, the gastritis segues to chronic atrophic gastritis, metaplasia, dysplasia and distal gastric cancer. Despite these well characterized clinical events, the link between inflammatory cytokines and non-cardia gastric cancer remains difficult to study in mouse models. Prior studies have demonstrated that overexpression of the Hedgehog (HH) effector GLI2 induces loss of gastrin (atrophy) and antral hyperplasia. To determine the link between specific cytokines, HH signaling and pre-neoplastic changes in the gastric antrum.
• Eijsbouts, C., Zheng, T., Kennedy, N. A., Bonfiglio, F., Anderson, C. A., Moutsianas, L., Holliday, J., Shi, J., Shringarpure, S., Agee, M., Aslibekyan, S., Auton, A., Bell, R. K., Bryc, K., Clark, S. K., Elson, S. L., Fletez-Brant, K., Fontanillas, P., Furlotte, N. A., , Gandhi, P. M., et al. (2021). Genome-wide analysis of 53,400 people with irritable bowel syndrome highlights shared genetic pathways with mood and anxiety disorders. Nature Genetics, 53(Issue 11). doi:10.1038/s41588-021-00950-8
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  Irritable bowel syndrome (IBS) results from disordered brain–gut interactions. Identifying susceptibility genes could highlight the underlying pathophysiological mechanisms. We designed a digestive health questionnaire for UK Biobank and combined identified cases with IBS with independent cohorts. We conducted a genome-wide association study with 53,400 cases and 433,201 controls and replicated significant associations in a 23andMe panel (205,252 cases and 1,384,055 controls). Our study identified and confirmed six genetic susceptibility loci for IBS. Implicated genes included NCAM1, CADM2, PHF2/FAM120A, DOCK9, CKAP2/TPTE2P3 and BAG6. The first four are associated with mood and anxiety disorders, expressed in the nervous system, or both. Mirroring this, we also found strong genome-wide correlation between the risk of IBS and anxiety, neuroticism and depression (rg > 0.5). Additional analyses suggested this arises due to shared pathogenic pathways rather than, for example, anxiety causing abdominal symptoms. Implicated mechanisms require further exploration to help understand the altered brain–gut interactions underlying IBS.
• Farshidpour, M., Ahmed, M., Junna, S., & Merchant, J. L. (2021). Myeloid-derived suppressor cells in gastrointestinal cancers: A systemic review. World journal of gastrointestinal oncology, 13(1), 1-11.
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  Gastrointestinal (GI) cancers are one of the most common malignancies worldwide, with high rates of morbidity and mortality. Myeloid-derived suppressor cells (MDSCs) are major components of the tumor microenvironment (TME). MDSCs facilitate the transformation of premalignant cells and play roles in tumor growth and metastasis. Moreover, in patients with GI malignancies, MDSCs can lead to the suppression of T cells and natural killer cells. Accordingly, a better understanding of the role and mechanism of action of MDSCs in the TME will aid in the development of novel immune-targeted therapies.
• Koh, V., Chakrabarti, J., Torvund, M., Steele, N., Hawkins, J. A., Ito, Y., Wang, J., Helmrath, M. A., Merchant, J. L., Ahmed, S. A., Shabbir, A., Yan So, J. B., Yong, W. P., & Zavros, Y. (2021). Hedgehog transcriptional effector GLI mediates mTOR-Induced PD-L1 expression in gastric cancer organoids. Cancer letters, 518, 59-71.
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  Tumors evade immune surveillance by expressing Programmed Death-Ligand 1 (PD-L1), subsequently inhibiting CD8 cytotoxic T lymphocyte function. Response of gastric cancer to immunotherapy is relatively low. Our laboratory has reported that Helicobacter pylori-induced PD-L1 expression within the gastric epithelium is mediated by the Hedgehog (Hh) signaling pathway. The PI3K/AKT/mTOR pathway is activated in gastric cancer and may have immunomodulatory potential. We hypothesize that Hh signaling mediates mTOR-induced PD-L1 expression. Patient-derived organoids (PDOs) were generated from gastric biopsies and resected tumor tissues. Autologous organoid/immune cell co-cultures were used to study the immunosuppressive function of MDSCs. NanoString Digital Spatial Profiling (DSP) of immune-related protein markers using FFPE slide-mounted tissues from gastric cancer patients was performed. DSP analysis showed infiltration of immunosuppressive MDSCs expressing Arg1, CD66b, VISTA and IDO1 within cancer tissues. Orthotopic transplantation of patient derived organoids (PDOs) resulted in the engraftment of organoids and the development of histology similar to that observed in the patient's tumor tissue. PDO/immune cell co-cultures revealed that PD-L1-expressing organoids were unresponsive to nivolumab in vitro in the presence of PMN-MDSCs. Depletion of PMN-MDSCs within these co-cultures sensitized the organoids to anti-PD-1/PD-L1-induced cancer cell death. Rapamycin decreased phosphorylated S6K, Gli2 and PD-L1 expression in PDO/immune cell co-cultures. Transcriptional regulation of PD-L1 by GLI1 and GLI2 was blocked by rapamycin. In conclusion, the PDO/immune cell co-cultures may be used to study immunosuppressive MDSC function within the gastric tumor microenvironment. The mTOR signaling pathway mediates GLI-induced PD-L1 expression in gastric cancer.
• Merchant, J. (2020). Interleukin-1β Suppresses Gastrin via Primary Cilia and Induces Antral Hyperplasia. Cell Mol Gastroenterol Hepatol.
• Rico, K., Duan, S., Pandey, R. L., Chen, Y., Chakrabarti, J. T., Starr, J., Zavros, Y., Else, T., Katona, B. W., Metz, D. C., & Merchant, J. L. (2021). Genome analysis identifies differences in the transcriptional targets of duodenal versus pancreatic neuroendocrine tumours. BMJ open gastroenterology, 8(1).
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  Gastroenteropancreatic neuroendocrine tumours (GEP-NETs) encompass a diverse group of neoplasms that vary in their secretory products and in their location within the gastrointestinal tract. Their prevalence in the USA is increasing among all adult age groups.
• Chakrabarti, J., Ding, L., Gupta, A., Mendoza, Z., Merchant, J. L., Sontz, R., & Zavros, Y. (2020). 354 INTERFERON ALPHA MEDIATES SCHLAFIN4+-MDSC POLARIZATION DURING HELICOBACTER-INDUCED SPASMOLYTIC POLYPEPTIDE-EXPRESSING METAPLASIA. Gastroenterology, 158(6), S-65-S-66. doi:10.1016/s0016-5085(20)30843-x
• Chakrabarti, J., Ding, L., Mendoza, Z., Merchant, J. L., Sontz, R., & Zavros, Y. (2020). 33 IN VIVO ADMINISTRATION OF ANTISENSE MIR130B BLOCKS HELICOBACTER-INDUCED SPASMOLYTIC POLYPEPTIDE-EXPRESSING METAPLASIA. Gastroenterology, 158(6), S-13. doi:10.1016/s0016-5085(20)30713-7
• Chakrabarti, J., Dua-awereh, M., Duan, S., Gupta, A., Katona, B. W., Khreiss, M., Merchant, J. L., Metz, D. C., Rico, K., Sheriff, S., & Zavros, Y. (2020). Sa1148 GENERATION AND CHARACTERIZATION OF HUMAN PANCREATIC NEUROENDOCRINE TUMOR ORGANOID: A CONFOCAL AND QPCR ANALYSIS.. Gastroenterology, 158(6), S-291. doi:10.1016/s0016-5085(20)31421-9
• Duan, S., Katona, B. W., Liang, Y., Merchant, J. L., Metz, D. C., Rico, K., Sheriff, S., & Zhang, L. (2020). 571 NOVEL DIGITAL SPATIAL PROFILING OF GASTROENTEROPANCREATIC NEUROENDOCRINE TUMOR REVEALS TISSUE SPECIFIC DIFFERENCES. Gastroenterology, 158(6), S-119. doi:10.1016/s0016-5085(20)30977-x
• Duan, S., Merchant, J. L., Rico, K., Sheriff, S., & Sontz, R. (2020). 573 EGF-INDUCED NUCLEAR EXPORT OF MENIN STIMULATES GASTRIN EXPRESSION IN VITRO AND COINCIDES WITH HYPERGASTRINEMIA IN A GLIAL-MEDIATED KNOCKOUT MOUSE MODEL OF MEN1. Gastroenterology, 158(6), S-120. doi:10.1016/s0016-5085(20)30979-3
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  significant differences in tumor site, race/ethnicity, and modified Charlson comorbidity score between those who did and did not receive SSA.In a multivariable model, the hazard ratio of developing DM with SSA treatment was 1.12, but this was not statistically significant (p= 0.24).Statistically significant risk factors for developing DM included tumor site in the pancreas or stomach, non-white race/ethnicity, prior pancreatic surgery, and higher modified Charlson comorbidity scores (Table 2).Conclusion: DM was a common comorbidity in NET patients, with an overall incidence of 24% after NET diagnosis in this cohort.Multivariable analysis did not show a significantly increased hazard of developing DM in patients treated with SSA.Further studies are needed to better understand this relationship.As NET patients have increasingly prolonged survival, it is crucial to identify chronic conditions these patients may be at higher risk for, especially conditions such as DM that cause significant morbidity and mortality.
• Merchant, J. (2020). A brief review of liver injury in patients with Corona Virus Disease-19 during the pandemic.. Indian journal of gastroenterology : official journal of the Indian Society of Gastroenterology.
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  The novel coronavirus Severe Acute Respiratory Syndrome Corona Virus-2 (SARS-CoV-2) infection has been mostly leading to respiratory distress syndrome, but liver injury has also been documented. The mechanism of liver injury is limited and poorly understood. However, the hepatic injury could be due to a consequence of systemic inflammatory response, viral infection of hepatocytes, or as a result of intensive care treatment or drug toxicity. Based on the current studies, this review article emphasizes on the demographic and potential mechanisms of Corona Virus Disease (COVID)-19-related liver dysfunction.
• Merchant, J. (2020). Interleukin-1β Suppresses Gastrin via Primary Cilia and Induces Antral Hyperplasia.. Cellular and molecular gastroenterology and hepatology.
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  BackgroundHelicobacter pylori infection in humans typically begins with colonization of the gastric antrum. The initial Th1 response occasionally coincides with an increase in gastrin secretion. Subsequently, the gastritis segues to chronic atrophic gastritis, metaplasia, dysplasia and distal gastric cancer. Despite these well characterized clinical events, the link between inflammatory cytokines and non-cardia gastric cancer remains difficult to study in mouse models. Prior studies have demonstrated that overexpression of the Hedgehog (HH) effector GLI2 induces loss of gastrin (atrophy) and antral hyperplasia.AimTo determine the link between specific cytokines, HH signaling and pre-neoplastic changes in the gastric antrum.MethodsMouse lines were created to conditionally direct IL-1β or IFNγ to the antrum using the Gastrin-CreERT2 and Tet activator. Primary cilia, which transduces HH signaling, on G cells were disrupted by deleting the ciliary motor protein KIF3a. Phenotypic changes were assessed by histology and western blots. A subclone of GLUTag enteroendocrine cells selected for gastrin expression and the presence of primary cilia was treated with recombinant SHH, IL-1β or IFNγ with or without kif3a siRNA.ResultsIFNγ increased gastrin and induced antral hyperplasia. However, antral expression of IL-1β suppressed tissue and serum gastrin, while also inducing antral hyperplasia. IFNγ treatment of GLUTAg cells suppressed GLI2 and induced gastrin, without affecting cilia length. By contrast, IL-1β treatment doubled primary cilia length, induced GLI2 and suppressed gastrin gene expression. Knocking down kif3a in GLUTAg cells mitigated SHH or IL-1β suppression of gastrin.ConclusionOverexpression of IL-1β in the antrum was sufficient to induce antral hyperplasia coincident with suppression of gastrin via primary cilia.
• Merchant, J. (2020). MiR130b from Schlafen4+ MDSCs stimulates epithelial proliferation and correlates with preneoplastic changes prior to gastric cancer.. Gut.
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  The myeloid differentiation factor Schlafen4 (Slfn4) marks a subset of myeloid-derived suppressor cells (MDSCs) in the stomach during Helicobacter-induced spasmolytic polypeptide-expressing metaplasia (SPEM). OBJECTIVE:To identify the gene products expressed by Slfn4+-MDSCs and to determine how they promote SPEM. DESIGN:We performed transcriptome analyses for both coding genes (mRNA by RNA-Seq) and non-coding genes (microRNAs using NanoString nCounter) using flow-sorted SLFN4+ and SLFN4- cells from Helicobacter-infected mice exhibiting metaplasia at 6 months postinfection. Thioglycollate-elicited myeloid cells from the peritoneum were cultured and treated with IFNα to induce the T cell suppressor phenotype, expression of MIR130b and SLFN4. MIR130b expression in human gastric tissue including gastric cancer and patient sera was determined by qPCR and in situ hybridisation. Knockdown of MiR130b in vivo in Helicobacter-infected mice was performed using Invivofectamine. Organoids from primary gastric cancers were used to generate xenografts. ChIP assay and Western blots were performed to demonstrate NFκb p65 activation by MIR130b. RESULTS:MicroRNA analysis identified an increase in MiR130b in gastric SLFN4+ cells. Moreover, MIR130b colocalised with SLFN12L, a human homologue of SLFN4, in gastric cancers. MiR130b was required for the T-cell suppressor phenotype exhibited by the SLFN4+ cells and promoted Helicobacter-induced metaplasia. Treating gastric organoids with the MIR130b mimic induced epithelial cell proliferation and promoted xenograft tumour growth. CONCLUSION:Taken together, MiR130b plays an essential role in MDSC function and supports metaplastic transformation.
• Merchant, J. (2020). Murine- and Human-Derived Autologous Organoid/Immune Cell Co-Cultures as Pre-Clinical Models of Pancreatic Ductal Adenocarcinoma.. Cancers.
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  Purpose: Pancreatic ductal adenocarcinoma (PDAC) has the lowest five-year survival rate of all cancers in the United States. Programmed death 1 receptor (PD-1)-programmed death ligand 1 (PD-L1) immune checkpoint inhibition has been unsuccessful in clinical trials. Myeloid-derived suppressor cells (MDSCs) are known to block anti-tumor CD8+ T cell immune responses in various cancers including pancreas. This has led us to our objective that was to develop a clinically relevant in vitro organoid model to specifically target mechanisms that deplete MDSCs as a therapeutic strategy for PDAC. Method: Murine and human pancreatic ductal adenocarcinoma (PDAC) autologous organoid/immune cell co-cultures were used to test whether PDAC can be effectively treated with combinatorial therapy involving PD-1 inhibition and MDSC depletion. Results: Murine in vivo orthotopic and in vitro organoid/immune cell co-culture models demonstrated that polymorphonuclear (PMN)-MDSCs promoted tumor growth and suppressed cytotoxic T lymphocyte (CTL) proliferation, leading to diminished efficacy of checkpoint inhibition. Mouse- and human-derived organoid/immune cell co-cultures revealed that PD-L1-expressing organoids were unresponsive to nivolumab in vitro in the presence of PMN-MDSCs. Depletion of arginase 1-expressing PMN-MDSCs within these co-cultures rendered the organoids susceptible to anti-PD-1/PD-L1-induced cancer cell death. Conclusions: Here we use mouse- and human-derived autologous pancreatic cancer organoid/immune cell co-cultures to demonstrate that elevated infiltration of polymorphonuclear (PMN)-MDSCs within the PDAC tumor microenvironment inhibit T cell effector function, regardless of PD-1/PD-L1 inhibition. We present a pre-clinical model that may predict the efficacy of targeted therapies to improve the outcome of patients with this aggressive and otherwise unpredictable malignancy.
• Merchant, J. (2020). ZBP-89 negatively regulates self-renewal of liver cancer stem cells via suppression of Notch1 signaling pathway. Cancer Letters.
• Ding, L., Li, Q., Munoz, A., Saqui-salces, M., & Merchant, J. L. (2019). 969 – Primary Cilia Transduce Inflammatory and Hedgehog Signaling to Modulate Gastrin Expression and Antral Hyperplasia. Gastroenterology, 156(6), S-203. doi:10.1016/s0016-5085(19)37301-9
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  developing ENS was performed by immunohistochemistry, confocal microscopy, RNAseq and qRT-PCR.Functionality, at the tissue level, was assessed using calcium imaging in conjunction with electrical point stimulation and pharmacological interrogation.Results: Human fetal gut samples displayed robust TuJ1 immunohistochemistry by embryonic week (EW) 12 with a dense neural network at the level of the myenteric plexus including expression of excitatory neurotransmitter (VAChT and SubP) and synaptic markers (SYN).By contrast, inhibitory neurotransmitter (nNOS and VIP) markers were not observed until EW14.Electrical train stimulation (40V, 2s, 20Hz of 300c ˇs electrical pulses) of internodal strands did not evoke activity within the myenteric plexus of EW12 fetal gut (n=0/3).Similarly, the majority of EW14 gut tissues (80%), assessed by calcium imaging, demonstrated no response to electrical stimulation (n=4/5).By contrast, at EW16 the emergence of evoked calcium transients (Fh/F0=1.21±0.03;n=3), upon electrical stimulation (n=3/3), was observed which were abolished after the addition of 1c ˇM tetrodotoxin (TTX; n=3/3).To investigate if postsynaptic specialization was a limiting factor in the development of evoked activity, pharmacological activation and blockade of nicotinic acetylcholine receptors was performed at EW14 and EW16 respectively.At EW14 application of 1c ˇM acetylcholine did not elicit compound activation within the presumptive ENS.Furthermore, by EW16 application of 300c ˇM hexamethonium did not diminish electrically evoked calcium transients whereas subsequent application of 1c ˇM TTX abolished compound activation of the fetal ENS.Expression analyses using RNAseq and qRT-PCR further showed that the development of evoked activity, within the developing ENS, is coincident with increases in expression of various genes encoding proteins involved in neurotransmission and action potential modulation.Conclusion: These findings provide the first direct evidence of developing neuronal diversity, electrical excitability and network formation in the human intestine.
• Ding, L., Li, Q., Munoz, A., Zavros, Y., Faure, E., Iliopoulos, D., Chakrabarti, J., & Merchant, J. L. (2019). 847 – Mir130B Expressed by Slfn4+-MDSCS Stimulates Epithelial Proliferation AND PRE-Neoplastic Changes. Gastroenterology, 156(6), S-186-S-187. doi:10.1016/s0016-5085(19)37256-7
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  Intestinal type gastric cancer develops from pre-cancerous lesions by a multistep process of pre-cancerous cell progression and evolution.Cancer stem cells (CSCs) have self-renewal capacity and can give rise to heterogeneous lineages in tumors.While many previous investigations have identified CSC markers in human gastric cancer, it remains unknown whether the CSCs are already present in pre-cancerous stages and if those CSCs can give rise to gastric cancer cells.In this study, we examined whether putative CSC populations exist in pre-cancerous stages and show stemness potential.We have recently established pre-neoplastic organoids (Meta4) from Mist1-Kras mice, which develop pre-neoplastic glands within 4 months following induction of constitutively-active Kras expression in chief cells.We treated the Meta4 organoids with Selumetinib, a MEK inhibitor, to target downstream mediators of Kras signaling pathway and evaluated altered cellular behaviors, structural changes and survival.The Meta4 organoids treated with Selumetinib for 3 days died or did not show an increase in size, while DMSO-treated organoids grew continuously.We next performed inDrop single cell-RNA sequencing (scRNA-seq) in Meta4 cells treated with either DMSO or Selumetinib to define cellular heterogeneity and subpopulations of Meta4.The scRNA-seq data analysis identified four distinct cell subpopulations in both samples.Interestingly, two subpopulations were associated with stem cell phenotypes and expressed several cancer stem cell markers, such as CD44, CD133 and CD166.We isolated two distinct subpopulations of Meta4 cells using the CSC markers, CD44+CD133+CD166+ (triple positive) and CD44-CD133+CD166+ (double positive), by flow cytometry analysis and performed clonal analysis to define the stemness of the isolated cells.The clonal analysis demonstrated that double-positive cells produced spheres more efficiently than triple-positive cells.We also co-stained for the CSC markers with Ki67, a proliferation marker, in pre-neoplastic stomach tissues of Mist1-Kras mice.We identified the two sub-populations at the base of glands in the mucosa.Many double-positive cells rather than triple-positive cells were copositive for Ki67.We additionally examined the expression of these CSC markers in human normal, metaplastic and gastric cancer tissues and observed the presence of the CSCs from the metaplastic stage.Collectively, these results indicate the functional heterogeneity of Meta4 cells and the presence of putative CSC populations in Meta4.Therefore, our study suggests that the putative CSC populations, present in the pre-cancerous stages, may be responsible for maintaining pre-cancerous heterogeneity and the cell state transition during pre-cancerous progression towards gastric cancer.
• Gupta, A., Ocadiz-ruiz, R., Attili, D., Dame, M. K., Brady, E., Turgeon, D. K., & Merchant, J. L. (2019). Mo1730 – Butyrate-Treated Colon Organoids from Fap Subjects Supresses Key Cancer Pathways When Zbp-89 (ZNF148) Deleted. Gastroenterology, 156(6), S-824. doi:10.1016/s0016-5085(19)39014-6
• Merchant, J. (2019). Generation of organoids from mouse extrahepatic bile ducts. Journal of Visualized Experiments.
• Merchant, J. (2019). Reduced efficacy of low FODMAPs diet in patients with IBS-D carrying sucrase-isomaltase (SI) hypomorphic variants.. Gut.
• Merchant, J. (2019). ZFP148 (Zinc-Finger Protein 148) Binds Cooperatively with NF-1 (Neurofibromin 1) to Inhibit Smooth Muscle Marker Gene Expression during Abdominal Aortic Aneurysm Formation. Arteriosclerosis, Thrombosis, and Vascular Biology.
• Razumilava, N., Shiota, J., Zaki, N. H., Ocadiz-ruiz, R., Cieslak, C. M., Zakharia, K., Allen, B. L., Gores, G. J., Samuelson, L. C., & Merchant, J. L. (2019). Hedgehog Signaling Modulates Interleukin-33-Dependent Extrahepatic Bile Duct Cell Proliferation in Mice.. Hepatology communications, 3(2), 277-292. doi:10.1002/hep4.1295
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  Hedgehog (HH) signaling participates in hepatobiliary repair after injury and is activated in patients with cholangiopathies. Cholangiopathies are associated with bile duct (BD) hyperplasia, including expansion of peribiliary glands, the niche for biliary progenitor cells. The inflammation-associated cytokine interleukin (IL)-33 is also up-regulated in cholangiopathies, including cholangiocarcinoma. We hypothesized that HH signaling synergizes with IL-33 in acute inflammation-induced BD hyperplasia. We measured extrahepatic BD (EHBD) thickness and cell proliferation with and without an IL-33 challenge in wild-type mice, mice overexpressing Sonic HH (pCMV-Shh), and mice with loss of the HH pathway effector glioma-associated oncogene 1 (Gli1lacZ/lacZ ). LacZ reporter mice were used to map the expression of HH effector genes in mouse EHBDs. An EHBD organoid (BDO) system was developed to study biliary progenitor cells in vitro. EHBDs from the HH overexpressing pCMV-Shh mice showed increased epithelial cell proliferation and hyperplasia when challenged with IL-33. In Gli1lacZ/lacZ mice, we observed a decreased proliferative response to IL-33 and decreased expression of Il6. The HH ligands Shh and Indian HH (Ihh) were expressed in epithelial cells, whereas the transcriptional effectors Gli1, Gli2, and Gli3 and the HH receptor Patched1 (Ptch1) were expressed in stromal cells, as assessed by in situ hybridization and lacZ reporter mice. Although BDO cells lacked canonical HH signaling, they expressed the IL-33 receptor suppression of tumorigenicity 2. Accordingly, IL-33 treatment directly induced BDO cell proliferation in a nuclear factor κB-dependent manner. Conclusion: HH ligand overexpression enhances EHBD epithelial cell proliferation induced by IL-33. This proproliferative synergism of HH and IL-33 involves crosstalk between HH ligand-producing epithelial cells and HH-responding stromal cells.
• Rico, K., Sheriff, S., Metz, D. C., Katona, B. W., Merchant, J. L., & Starr, J. A. (2019). 634 – Genome Analysis of Duodenal Gastrinomas and Pancreatic Neuroendocrine Tumors Reveal Differential Location of Men1 Mutations Linked to Tissue Specific Phenotype. Gastroenterology, 156(6), S-134. doi:10.1016/s0016-5085(19)37125-2
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  in our institution over the last 3 years.Using the Electronic Health Records system, we collected data on tumor histology, presenting symptoms, biomarkers, and other imaging.Results: Of all 994 patients with NEN who had a Ga-68-DOTATATE PET, 677 (63%) had GEP-NEN.The primary was mainly in small bowel in 413/677 (61%), followed by pancreas in 182 (27%).Liver was the most common site of metastases (348/677, 51%), followed by the spine (127,19%).The latter had not been reported in previous CT and/or OctreoScan in 47/127 (37%) patients.Metastases in: myocardium were revealed in 16/677 (2.4%), breast in 13/677 (1.9%), orbits in 9/677 (1.3%) and brain metastases in 2/677 (0.2%) patients.Those rare metastases were subsequently confirmed by MRI heart/brain/orbits, US breast and biopsy of breast lesions, respectively.Brain metastases and the majority of breast and myocardial metastases had not been noted in previous CTs or Octreoscans.On the contrary, orbital metastases had already been demonstrated in 5/9 (55.5%) patients on previous OctreoScans.Ga-68 DOTATATE was avid in 16/18 (90%), of well-differentiated G3 neuroendocrine tumours (NET), with Ki67
• Salmon, M., Schaheen, B., Spinosa, M., Montgomery, W., Pope, N. H., Davis, J. P., Johnston, W. F., Sharma, A. K., Owens, G. K., Merchant, J. L., Zehner, Z. E., Upchurch, G. R., & Ailawadi, G. (2019). ZFP148 (Zinc-Finger Protein 148) Binds Cooperatively with NF-1 (Neurofibromin 1) to Inhibit Smooth Muscle Marker Gene Expression during Abdominal Aortic Aneurysm Formation. Arteriosclerosis, Thrombosis, and Vascular Biology, 39(Issue 1). doi:10.1161/atvbaha.118.311136
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  The goal of this study was to determine the role of ZFP148 (zinc-finger protein 148) in aneurysm formation. Approach and Results - ZFP148 mRNA expression increased at day 3, 7, 14, 21, and 28 after during abdominal aortic aneurysm formation in C57BL/6 mice. Loss of ZFP148 conferred abdominal aortic aneurysm protection using ERTCre+ ZFP148 flx/flx mice. In a third set of experiments, smooth muscle-specific loss of ZFP148 alleles resulted in progressively greater protection using novel transgenic mice (MYH [myosin heavy chain 11] Cre+ flx/flx, flx/wt, and wt/wt). Elastin degradation, LGAL3, and neutrophil staining were significantly attenuated, while -actin staining was increased in ZFP148 knockout mice. Results were verified in total cell ZFP148 and smooth muscle-specific knockout mice using an angiotensin II model. ZFP148 smooth muscle-specific conditional mice demonstrated increased proliferation and ZFP148 was shown to bind to the p21 promoter during abdominal aortic aneurysm formation. ZFP148 smooth muscle-specific conditional knockout mice also demonstrated decreased apoptosis as measured by decreased cleaved caspase-3 staining. ZFP148 bound smooth muscle marker genes via chromatin immunoprecipitation analysis mediated by NF-1 (neurofibromin 1) promote histone H3K4 deacetylation via histone deacetylase 5. Transient transfections and chromatin immunoprecipitation analyses demonstrated that NF-1 was required for ZFP148 protein binding to smooth muscle marker genes promoters during aneurysm formation. Elimination of NF-1 using shRNA approaches demonstrated that NF-1 is required for binding and elimination of NF-1 increased BRG1 recruitment, the ATPase subunit of the SWI/SWF complex, and increased histone acetylation. Conclusions - ZFP148 plays a critical role in multiple murine models of aneurysm formation. These results suggest that ZFP148 is important in the regulation of proliferation, smooth muscle gene downregulation, and apoptosis in aneurysm development.
• Sheriff, S., Rico, K., Pandey, R., Katona, B. W., Metz, D. C., Merchant, J. L., Mandape, S. N., & Starr, J. A. (2019). 636 – Duodenal Neuroendocrine Tumors Exhibit Distinct Somatic Mutations Compared to Pancreatic Neuroendocrine Tumors and Ileal Carcinoids. Gastroenterology, 156(6), S-134. doi:10.1016/s0016-5085(19)37127-6
• Merchant, J. (2018). Hedgehog Signaling Modulates Interleukin-33-Dependent Extrahepatic Bile Duct Cell Proliferation in Mice.. Hepatology communications.
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  Hedgehog (HH) signaling participates in hepatobiliary repair after injury and is activated in patients with cholangiopathies. Cholangiopathies are associated with bile duct (BD) hyperplasia, including expansion of peribiliary glands, the niche for biliary progenitor cells. The inflammation-associated cytokine interleukin (IL)-33 is also up-regulated in cholangiopathies, including cholangiocarcinoma. We hypothesized that HH signaling synergizes with IL-33 in acute inflammation-induced BD hyperplasia. We measured extrahepatic BD (EHBD) thickness and cell proliferation with and without an IL-33 challenge in wild-type mice, mice overexpressing Sonic HH (pCMV-Shh), and mice with loss of the HH pathway effector glioma-associated oncogene 1 (Gli1lacZ/lacZ ). LacZ reporter mice were used to map the expression of HH effector genes in mouse EHBDs. An EHBD organoid (BDO) system was developed to study biliary progenitor cells in vitro. EHBDs from the HH overexpressing pCMV-Shh mice showed increased epithelial cell proliferation and hyperplasia when challenged with IL-33. In Gli1lacZ/lacZ mice, we observed a decreased proliferative response to IL-33 and decreased expression of Il6. The HH ligands Shh and Indian HH (Ihh) were expressed in epithelial cells, whereas the transcriptional effectors Gli1, Gli2, and Gli3 and the HH receptor Patched1 (Ptch1) were expressed in stromal cells, as assessed by in situ hybridization and lacZ reporter mice. Although BDO cells lacked canonical HH signaling, they expressed the IL-33 receptor suppression of tumorigenicity 2. Accordingly, IL-33 treatment directly induced BDO cell proliferation in a nuclear factor κB-dependent manner. Conclusion: HH ligand overexpression enhances EHBD epithelial cell proliferation induced by IL-33. This proproliferative synergism of HH and IL-33 involves crosstalk between HH ligand-producing epithelial cells and HH-responding stromal cells.
• Merchant, J. (2018). Indian Hedgehog Suppresses Intestinal Inflammation. Cellular and Molecular Gastroenterology and Hepatology.
• Merchant, J. (2018). Isolation of enteric glial cells from the submucosa and lamina propria of the adult mouse. Journal of Visualized Experiments.
• Merchant, J. (2018). Mature enteroendocrine cells contribute to basal and pathological stem cell dynamics in the small intestine. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2018). Parietal Cell Death by Cytokines. Cellular and Molecular Gastroenterology and Hepatology.
• Eswaran, S. L., Merchant, J. L., Photenhauer, A., Jackson, K., Madriaga, D., Selvaraj, F. M., Princen, F., & Chey, W. D. (2017). Tryptophan Hydroxlase 1 (TPH1) Promoter Genotype but not Serum Serotonin Levels Identify IBS-D Patients More Likely to Benefit from the Low Fodmap Diet. Gastroenterology, 152(5), S69. doi:10.1016/s0016-5085(17)30585-1
• Merchant, J. (2017). A Summary of the 2016 James W. Freston Conference of the American Gastroenterological Association: Intestinal Metaplasia in the Esophagus and Stomach: Origins, Differences, Similarities and Significance. Gastroenterology.
• Merchant, J. (2017). Deletion of Men1 and somatostatin induces hypergastrinemia and gastric carcinoids. Gut.
• Merchant, J. (2017). Gastric Acid Secretion from Parietal Cells Is Mediated by a Ca²⁺ Efflux Channel in the Tubulovesicle. Developmental Cell.
• Merchant, J. (2017). Gastrin Induces Nuclear Export and Proteasome Degradation of Menin in Enteric Glial Cells. Gastroenterology.
• Merchant, J. (2017). Hedgehog Signaling Links Chronic Inflammation to Gastric Cancer Precursor Lesions. Cellular and Molecular Gastroenterology and Hepatology.
• Merchant, J. (2017). Pathophysiology of Gastric NETs: Role of Gastrin and Menin. Current Gastroenterology Reports.
• Merchant, J. (2017). SCHLAFEN 5 expression correlates with intestinal metaplasia that progresses to gastric cancer. Journal of Gastroenterology.
• Merchant, J. (2017). Weight gain in mice on a high caloric diet and chronically treated with omeprazole depends on sex and genetic background. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2017). ZBP-89 function in colonic stem cells and during butyrateinduced senescence. Oncotarget.
• Merchant, J. L. (2017). NF-κB mediated transcription of DARPP-32 prevents Helicobacter pylori-induced cell death.. Gut, 66(5), 761-762. doi:10.1136/gutjnl-2016-312822
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  Gastric cancer remains one of the leading neoplasms and currently ranks third in cancer mortality worldwide.1 Helicobacter pylori ( H. pylori ) infection, and the subsequent chronic inflammation that the organism induces, is a major risk factor for stomach cancer,2 along with smoking and a diet high in salt and nitrates (http://www.cancer.org/cancer/stomachcancer/detailedguide/stomach-cancer-risk-factors). Within the past several years, the focus on aetiology has shifted from epidemiology to understanding the genomic landscape that occurs during gastric transformation. Specifically, the gastric cancer genome analysis demonstrated that specific molecular signatures classify this cancer into at least four subtypes that can serve as the basis for patient stratification and precision therapies.3 ,4 Prior to whole genome analysis of gastric cancer, analysis of chromosomal abnormalities identified 17q12–21 as the site of DNA amplification in gastric cancer.5 Subsequently, El-Rifai and coworkers identified an expressed sequence tag (EST) that was one of the most frequently amplified genes at 17q12, and when sequenced corresponded to the 3′ untranslated region of the DARPP-32 (dopamine and cAMP-regulated phosphoprotein 32 000 Da) locus which encodes a phosphoprotein regulated by dopamine and cAMP.6–8 Overexpression of DARPP-32 in gastric cancer cell lines blocks fatty acid induced apoptosis, demonstrating its antiapoptotic effect.7 DARPP-32 also exists as a splice variant called t-DARPP. This truncated version of the DARPP-32 protein (168 residues) is missing …
• Ocadiz-ruiz, R., Hayes, M. M., & Merchant, J. L. (2017). Transcription Factor ZBP-89 Cooperates with B-Catenin in the Lgr5+ Stem Cell. Gastroenterology, 152(5), S20. doi:10.1016/s0016-5085(17)30442-0
• Ding, L., Merchant, J. L., & Zaatari, M. E. (2016). Recapitulating Human Gastric Cancer Pathogenesis: Experimental Models of Gastric Cancer.. Advances in experimental medicine and biology, 908, 441-78. doi:10.1007/978-3-319-41388-4_22
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  This review focuses on the various experimental models to study gastric cancer pathogenesis, with the role of genetically engineered mouse models (GEMMs) used as the major examples. We review differences in human stomach anatomy compared to the stomachs of the experimental models, including the mouse and invertebrate models such as Drosophila and C. elegans. The contribution of major signaling pathways, e.g., Notch, Hedgehog, AKT/PI3K is discussed in the context of their potential contribution to foregut tumorigenesis. We critically examine the rationale behind specific GEMMs, chemical carcinogens, dietary promoters, Helicobacter infection, and direct mutagenesis of relevant oncogenes and tumor suppressor that have been developed to study gastric cancer pathogenesis. Despite species differences, more efficient and effective models to test specific genes and pathways disrupted in human gastric carcinogenesis have yet to emerge. As we better understand these species differences, "humanized" versions of mouse models will more closely approximate human gastric cancer pathogenesis. Towards that end, epigenetic marks on chromatin, the gut microbiota, and ways of manipulating the immune system will likely move center stage, permitting greater overlap between rodent and human cancer phenotypes thus providing a unified progression model.
• Jacob, N., Benhammou, J. N., Yu, C., Shojamanesh, H., Metz, D. C., Sedarat, A., Lewis, M. P., Merchant, J. L., & Pisegna, J. R. (2016). Characteristics of Duodenal Neuroendocrine Tumors (DNETs) and Establishment of a Natural History and Genetics Registry: 1085. The American Journal of Gastroenterology, 111, S474. doi:10.14309/00000434-201610001-01085
• Merchant, J. (2016). Invasive mouse gastric adenocarcinomas arising from Lgr5+ stem cells are dependent on crosstalk between the Hedgehog/GLI2 and mTOR pathways. Oncotarget.
• Merchant, J. (2016). NF-κB mediated transcription of DARPP-32 prevents Helicobacter pylori-induced cell death. Gut.
• Merchant, J. (2016). Schlafen 4-expressing myeloid-derived suppressor cells are induced during murine gastric metaplasia. Journal of Clinical Investigation.
• Merchant, J. (2016). Transcription factor ZBP-89 drives a feedforward loop of β-catenin expression in colorectal cancer. Cancer Research.
• Merchant, J. L., Photenhauer, A., Eswaran, S. L., Jackson, K., & Chey, W. D. (2016). Tu1807 A US, Randomized, Controlled Trial Comparing the Low FODMAP Diet vs NICE Guidelines in Adults IBS-D Adults: Predictive Value of a Tryptophan Hydroxlase 1 (TPH1) Promoter Variant. Gastroenterology, 150(4), S953. doi:10.1016/s0016-5085(16)33218-8
• Salmon, M., Fashandi, A. Z., Spinosa, M., Sharma, A., Owens, G. K., Merchant, J. L., Zehner, Z. E., Upchurch, G. R., & Ailawadi, G. (2016). Abstract 436: Smooth Muscle Specific Knock-out of the Zinc-Finger Protein 148(ZFP148) Attenuates Atherosclerotic Lesion Formation via Regulation of Apoptotic Signaling Pathways. Arteriosclerosis, Thrombosis, and Vascular Biology, 36. doi:10.1161/atvb.36.suppl_1.436
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  Objective: Zinc-finger protein 148 (ZFP148) plays a profound role in the modulation of aortic aneurysm formation in part via modulation of smooth muscle (SMC) genes. The current study objective was to determine whether smooth muscle specific knock-out of ZFP148 is critical in atherosclerotic lesion formation. Methods: ZFP148 was examined via immunohistochemistry and confocal microscopy in human atherosclerotic lesion samples (n=12/group). 6-8 week male (n=12/group) ZFP flx/flx Myh11 Cre+ ApoE-/-(SMC tamoxifen ZFP148 KO), Myh11 ZFP148 flx/wt Cre+ ApoE-/- and Myh11 ZFP wt/wt Cre+ ApoE-/- underwent tamoxifen injections followed by western diet feeding for either 13 or 25 weeks. A separate set of mice were fed western diet for 18 weeks and then administered tamoxifen injections. Aortic samples were evaluated with histology for α-actin, macrophages, neutrophils, TER119, caspase3, Ki67, picosirus red and movat staining. In vitro ZFP148 was knocked down using siRNA in smooth muscle cells and stimulated with the oxidized phospholipid POVPC. Results: ZFP148 expression was elevated in human atherosclerotic lesion samples and localized to smooth muscle cells. Lesion size was significantly reduced in SMC ZFP148 KO mice compared with controls in 25 week western diet fed mice(p Conclusions: While earlier studies documented a role for ZFP148 in aneurysm disease, the present study suggests that SMC ZFP148 KO attenuates atherosclerotic lesion formation in early and late atherosclerotic disease. ZFP148 represents a key regulator of multiple types of vascular disease.
• Essien, B. E., Stoffel, E. M., Photenhauer, A., Tsao, A. C., & Merchant, J. L. (2015). Mo2007 ZBP-89 (ZNF148) Cooperates With HNF1A, a Transcriptional Regulator Mutated in Colorectal Cancer Before Age 50. Gastroenterology, 148(4), S-766. doi:10.1016/s0016-5085(15)32616-0
• Essien, B. E., Yang, A., Tessier, A. J., Marquette, A., Tsao, A. C., Photenhauer, A., Shah, Y. M., Gyorffy, B., & Merchant, J. L. (2015). 404 ZBP-89 Recruits Hdacs to β-Catenin Target Genes Regulated by Butyrate Contributing to Colorectal Cancer Progression and Heterogeneity. Gastroenterology, 148(4), S-86. doi:10.1016/s0016-5085(15)30298-5
• Grasberger, H., Gao, J., Nagao-Kitamoto, H., Kitamoto, S., Zhang, M., Kamada, N., Eaton, K. A., El-Zaatari, M., Shreiner, A. B., Merchant, J. L., Owyang, C., & Kao, J. Y. (2015). Increased Expression of DUOX2 Is an Epithelial Response to Mucosal Dysbiosis Required for Immune Homeostasis in Mouse Intestine. GASTROENTEROLOGY, 149(7), 1849-1859.
• Merchant, J. (2015). Increased Expression of DUOX2 Is an Epithelial Response to Mucosal Dysbiosis Required for Immune Homeostasis in Mouse Intestine. Gastroenterology.
• Merchant, J. (2015). Pilot study of Biomarkers for predicting effectiveness of ramosetron in diarrhea-predominant irritable bowel syndrome: Expression of S100A10 and polymorphisms of TPH1. Neurogastroenterology and Motility.
• Photenhauer, A., Essien, B. E., & Merchant, J. L. (2015). Mo1860 In Vivo ZBP-89 Expression in the Intestinal and Colonic Stem Cell Niche. Gastroenterology, 148(4), S-728-S-729. doi:10.1016/s0016-5085(15)32489-6
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  prescribed GABA A receptor agonists -benzodiazepines and zolpidem -to CDI development.Results: High risk patients (n=150) or subjects being tested for CDI (n=275) in 3 different hospitals from 2009-2014 were included in the study.Patients who developed CDI had significant antibiotic-associated shifts in microbiome and metabolome signatures that were functionally-associated with increased L-arginine conversion to GABA.Elevated stool GABA was predictive of disease susceptibility and recurrence in both patients and in experimental CDI models.Mechanistically, GABA inhibited protective serum antitoxin titers -a clinical predictor of disease susceptibility -and potentiated toxin virulence via activation of GABA A receptor signaling.Multivariate logistic regression analysis demonstrated that zolpidem use in high risk patients was significantly associated with CDI onset (OR: 4.88; 95% CI 1.25 -18.34; p
• Salmon, M., Wu, A., Shankman, L. S., Greene, E. S., Zehner, Z. E., Merchant, J. L., Owens, G. K., Upchurch, G. R., & Ailawadi, G. (2015). Abstract 189: The Zinc-finger Protein 148(zfp148) Modulates Smooth Muscle Marker Genes via Interaction With Nf-1 in Vascular Disease. Arteriosclerosis, Thrombosis, and Vascular Biology, 35. doi:10.1161/atvb.35.suppl_1.189
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  Objective: We and others have shown that smooth muscle (SMC) marker gene down-regulation is an early event in vascular disease and involves the transcription factor KLF4. However, the molecular mechanisms mediating continued repression following KLF4 release remain unknown. Recently, we have shown that ZFP148 is critical in SMCs during aortic aneurysm formation; however, no studies have investigated the molecular mechanisms of this process. The study objective was to determine what factors mediate SMC down-regulation after KLF4 binding is diminished. Methods and Results: 8-12 week male mice (n=8 per group) underwent carotid ligation and were harvested at day 7 for chromatin immunoprecipitation analysis (ChIP) for KLF4, KLF2, ZFP148, NF-1, Sp1, Sp3 and YY1. ZFP148, NF-1 and KLF2 were significantly elevated following ligation injury. In separate experiments, 8-12 week male (n=10/group) C57/B6 mice underwent carotid ligation and were harvested at 1, 3, 7, and 14, days for ChIP analysis for ZFP148 and NF-1. Z...
• Stoffel, E. M., Koeppe, E. S., Zuhlke, K. A., Appelman, H. D., Essien, B. E., Photenhauer, A., Cooney, K. A., Merchant, J. L., & Rozek, L. S. (2015). Su1941 Germline Variant in Hnf1a Is Overrepresented Among Individuals With Young Onset Colorectal Cancer. Gastroenterology, 148(4), S-556. doi:10.1016/s0016-5085(15)31870-9
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  for the occurence of colorectal tumors.A functional study was designed to assess the influence of polymorphisms on COX-2, HPGD, SLCO2A1 and ABCC4 mRNA levels on colonic tissues from 60 patients diagnosed with CRC.RNA was extracted from formalin-fixed paraffinembedded (FFPE) and examined by real-time PCR using validated human hydrolysis Probe/ Primer assays (Hs00153133_m1, Hs00960586_g1, Hs00194554_m1 and Hs00988717_m1, respectively).The fold difference in expression was determined following the Livak method.Thirteen polymorphisms were shown to have an allelic-specific expression profile.The rs689466GG genotype was associated with a 7-fold overexpression of COX-2 in CRC tissues (-1.57±0.10vs -4.42±1.58 for the AA genotype, P=0.014).Similarly, the heterozygous genotype for the rs1425945 polymorphism exhibited a trend for higher levels of HPGD (-1.10±1.41vs -2.02±2.18for the GG homozygous genotype, P=0.163).An approximately 2-fold overexpression was reported for AC and CC genotype of rs9820625 tagSNPs in SLCO2A1 when compared with the AA homozygous genotype in normal-appearing mucosa (-4.96±1.78 and -5.17±1.28vs -6.08±0.96,respectively, P=0.024).Furthermore, the ABCC4 levels were progressively lower in rs1678405TC and CC genotypes in malignant mucosa (-2.26±1.47 and -3.39±0.92,respectively, vs -1.43±1.18 with the TT genotype, P=0.049).The present study reports the involvement of genetic variants on COX-2, HPGD, SLCO2A1, ABCC4 genes' expression providing a biological reasoning underlying the epidemiological data that might allow the identification of individuals for targetted strategies in colorectal cancer prevention.
• Ding, L., Hayes, M. M., Tsao, A. C., & Merchant, J. L. (2014). 265 Hedgehog/Gli1 Signaling Regulates Phenotypic Changes in Myeloid Cells During Helicobacter-Induced SPEM (Gastric Metaplasia). Gastroenterology, 146(5), S-63. doi:10.1016/s0016-5085(14)60224-9
• Essien, B. E., Yang, A., & Merchant, J. L. (2014). 597 Transcription Factor ZBP-89 Protects the Colon From AOM/DSS-Induced Tumorigenesis by Interacting With β-Catenin. Gastroenterology, 146(5), S-113. doi:10.1016/s0016-5085(14)60405-4
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  Background: Transcription factor Zinc-finger Binding Protein-89 (ZBP-89, ZNF148) expression is regulated by butyrate and forms protein-protein complexes with tumor suppressor factors, e.g.p53, p300, ataxia-telangiectasia mutated (ATM).To study the role of ZBP-89 in vivo, we generated a conditional knockout in the intestine and colon (ZBP-89ΔInt).Mice exhibited increased morbidity and mortality when challenged with Salmonella typhimurium, in part due to reduced tryptophan hydroxylase 1(Tph1) expression and reduced colonic antimicrobial peptide secretion (defensins).We found that β-catenin cooperates with ZBP-89 to induce tryptophan hydroxylase 1(Tph1) expression in enterochromaffin cells.Aim: To determine whether ZBP-89 interacts directly with β-catenin to prevent colonic transformation.Methods: ZBP-89ΔInt and WT littermates were treated with 7.4mg/kg azoxymethane (AOM) and water containing 2% dextran sulfate sodium (DSS).After 3 cycles, mice were sacrificed 5 weeks later for tumor evaluation, mRNA and histological analysis.Expression of β-catenin-TCF gene targets was determined by rt-qPCR on colonic lysates.The ZBP-89 expression vector was co-transfected with or without β-catenin into HEK293 or SW480, a human colorectal cell line with the TCF reporter plasmid TOPFLASH to assess direct regulation of Wnt-β-catenin-TCF transcriptional activity.To demonstrate the association of ZBP-89 with β-catenin, cell lysates of SW480 were used to perform co-immunoprecipitation.Results: We observed 100% increase in tumor incidence and size in the distal colon and rectum of ZBP-89ΔInt compared to WT mice after the administration of AOM/DSS, N=16 mice/group (P
• Merchant, J. (2014). Inhibition of Hedgehog signaling in the gastrointestinal tract: Targeting the cancer microenvironment. Cancer Treatment Reviews.
• Merchant, J. (2014). Stress hematopoiesis is regulated by the Krüppel-like transcription factor ZBP-89. Stem Cells.
• Salmon, M., Pope, N. H., Johnston, W. F., Davis, J. P., Owens, G. K., Merchant, J. L., Upchurch, G. R., & Ailawadi, G. (2014). Abstract 19212: The Zinc-finger Protein 148(zfp148) Attenuates Aortic Aneurysm Formation and is a Novel Smooth Muscle Cell Regulator. Circulation, 130. doi:10.1161/circ.130.suppl_2.19212
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  Objective: Previously, we found that the zinc-finger protein 148(ZFP148) binds to smooth muscle(SMC) genes following ligation injury; however, it has no known role in aortic aneurysm formation. The study objective was to determine whether ZFP148 is important in AA formation. Methods: ZFP148 was examined via qPCR in human aortic aneurysms(n=12/group). 8-12 week male C57/B6 mice (n=6/group) underwent elastase perfusion and were harvested at 3, 7, and 14 days for qPCR for ZFP148. Separately, 8-12 week male (n=10/group) ZFP flx/flx Myh11 Cre+(SMC tamoxifen ZFP148 KO), Myh11 ZFP148 flx/wt Cre+ and Myh11 ZFP wt/wt Cre+ underwent elastase perfusion. At 14 days, maximal aortic dilation was measured with video micrometry. ZFP148 flx/flx ERT Cre+ (n=10/group) and ZFP148 flx/flx ERT Cre-(WT) mice also underwent elastase perfusion. A separate set of mice were bred to an ApoE-/- background and administered Angiotensin II via osmotic pump. Aortic samples were evaluated with histology for α-actin, macrophages, neutrophi...
• Saqui-salces, M., Tsao, A. C., & Merchant, J. L. (2014). Su1917 Chronic Omeprazole Treatment Induces Weight Gain in Mice When Combined to High Energy Diet. Gastroenterology, 146(5), S-501. doi:10.1016/s0016-5085(14)61806-0
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  of corticosterone level to baseline in 4 h after indomethacin administration. Indomethacininduced corticosterone rise was inhibited by NBI 27914 injection and these results confirm the critical role of CRF1 receptors in the activation of the HPA axis. Both astressin and astressin2-B injection resulted in a delay of the recovery to basal circulating corticosterone levels. The impaired termination of corticosterone response to indomethacin caused by astressin2-B was followed by aggravation of indomethacin-induced gastric injury. Conclusions: The results suggest that CRF injected into the periphery at the dose, which markedly increased plasma corticosterone levels, may induce protection against indomethacin-produced gastric injury through both CRF1 and CRF2 receptors. CRF2 receptor signaling pathway contributes to the appropriate termination of indomethacin-induced corticosterone secretion and the maintainance of gastric mucosal integrity during ulcerogenic action of indomethacin in rats. The study was supported by grants from RFBR N13-04-01680a and PRAS 5 and 7.
• Todt, J., Tsao, A. C., Hayes, M. M., Veniaminova, N. A., Saqui-salces, M., & Merchant, J. L. (2014). Sa1811 Generation of Gastric Carcinoids in Mice After Targeted Deletion of Men1 and Somatostatin Gene Loci. Gastroenterology, 146(5), S-300. doi:10.1016/s0016-5085(14)61080-5
• El-Zaatari, M., Kao, J. Y., Tessier, A., Bai, L., Hayes, M. M., Fontaine, C., Eaton, K. A., & Merchant, J. L. (2013). Gli1 Deletion Prevents Helicobacter-Induced Gastric Metaplasia and Expansion of Myeloid Cell Subsets. PLOS ONE, 8(3).
• Essien, B. E., Grasberger, H., Romain, R. D., Law, D. J., Veniaminova, N. A., Saqui-Salces, M., El-Zaatari, M., Tessier, A., Hayes, M. M., Yang, A. C., & Merchant, J. L. (2013). ZBP-89 Regulates Expression of Tryptophan Hydroxylase I and Mucosal Defense Against Salmonella Typhimurium in Mice. GASTROENTEROLOGY, 144(7), 1466-U254.
• Grasberger, H., Chang, L., Shih, W., Presson, A. P., Sayuk, G. S., Newberry, R. D., Karagiannides, I., Pothoulakis, C., Mayer, E., & Merchant, J. L. (2013). Identification of a Functional TPH1 Polymorphism Associated With Irritable Bowel Syndrome Bowel Habit Subtypes. AMERICAN JOURNAL OF GASTROENTEROLOGY, 108(11), 1766-1774.
• Grasberger, H., El-Zaatari, M., Dang, D. T., & Merchant, J. L. (2013). Dual Oxidases Control Release of Hydrogen Peroxide by the Gastric Epithelium to Prevent Helicobacter felis Infection and Inflammation in Mice. GASTROENTEROLOGY, 145(5), 1045-1054.
• Merchant, J. (2013). Dual oxidases control release of hydrogen peroxide by the gastric epithelium to prevent helicobacter felis infection and inflammation in mice. Gastroenterology.
• Merchant, J. (2013). Epigenetic upregulation of Bak by ZBP-89 inhibits the growth of hepatocellular carcinoma. Biochimica et Biophysica Acta - Molecular Cell Research.
• Merchant, J. (2013). Gli1 Deletion Prevents Helicobacter-Induced Gastric Metaplasia and Expansion of Myeloid Cell Subsets. PLoS ONE.
• Merchant, J. (2013). Identification of a functional TPH1 polymorphism associated with irritable bowel syndrome bowel habit subtypes. American Journal of Gastroenterology.
• Merchant, J. (2013). ZBP-89 regulates expression of tryptophan hydroxylase i and mucosal defense against salmonella typhimurium in mice. Gastroenterology.
• Berndt, B. E., Zhang, M., Owyang, S. Y., Cole, T. S., Wang, T. W., Luther, J., Veniaminova, N. A., Merchant, J. L., Chen, C., Huffnagle, G. B., & Kao, J. Y. (2012). Butyrate increases IL-23 production by stimulated dendritic cells. AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY, 303(12), G1384-G1392.
• Chavis, A. R., Hayes, M. M., Essien, B. E., & Merchant, J. L. (2012). 516 Deletion of Transcription Factor ZBP-89 Inhibits Polyp Formation in Mutant APC Mice. Gastroenterology, 142(5), S-108. doi:10.1016/s0016-5085(12)60407-7
• El-zaatari, M., Kao, J. Y., Hayes, M. M., Tessier, A., Fontaine, C., Eaton, K. A., Gumucio, D. L., & Merchant, J. L. (2012). 237 Gli-1 Deficiency Blocks Inflammation and Subsequent Metaplasia During Helicobacter felis Infection. Gastroenterology, 142(5), S-58. doi:10.1016/s0016-5085(12)60226-1
• El-zaatari, M., Kao, J. Y., Tessier, A., Hayes, M. M., Gumucio, D. L., & Merchant, J. L. (2012). 261 Two Hedgehog (GLI1) Gene Targets Correlate With Helicobacter-Induced Antigen-Presenting Cell Recruitment. Gastroenterology, 142(5), S-61. doi:10.1016/s0016-5085(12)60239-x
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  findings, we propose a two-compartment model in which increased local production of Egfr ligands act on heightened levels of ErbBs in the epithelium to predispose to neoplasia.Moreover, these results provide the first In Vivo evidence that Lrig1 acts as a tumor suppressor.
• Essien, B. E., Grasberger, H., & Merchant, J. L. (2012). 160 Salmonella Typhimurium SPI-1 Encodes Factors That Inhibit Colonic ZBP-89-Regulation of Tryptophan Hydroxylase 1 (TPH1). Gastroenterology, 142(5), S-39. doi:10.1016/s0016-5085(12)60149-8
• Essien, B. E., Grasberger, H., Tessier, A., & Merchant, J. L. (2012). Mo1768 ZBP-89 Essential for TPH1 Expression and Innate Mucosal Immunity. Gastroenterology, 142(5), S-680. doi:10.1016/s0016-5085(12)62622-5
• Essien, B., & Merchant, J. L. (2012). Butyrate regulation of tryptophan hydroxylase 1 and serotonin (5HT) requires transcription factor ZBP-89. Regulatory Peptides, 177, S20. doi:10.1016/j.regpep.2012.05.033
• Merchant, J. (2012). A high-fat diet regulates gastrin and acid secretion through primary cilia. FASEB Journal.
• Merchant, J. (2012). Butyrate increases IL-23 production by stimulated dendritic cells. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2012). Conditional deletion of menin results in antral G cell hyperplasia and hypergastrinemia. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2012). Hedgehog signalling in gut development, physiology and cancer. JOURNAL OF PHYSIOLOGY-LONDON, 590(3), 421-432.
• Merchant, J. (2012). Hedgehog signalling in gut development, physiology and cancer. Journal of Physiology.
• Merchant, J. (2012). IFNγ contributes to the development of gastric epithelial cell metaplasia in Huntingtin interacting protein 1 related (Hip1r)-deficient mice. Laboratory Investigation.
• Merchant, J. (2012). Inflammation and Gli2 Suppress Gastrin Gene Expression in a Murine Model of Antral Hyperplasia. PLoS ONE.
• Merchant, J. (2012). Interaction between ZBP-89 and p53 mutants and its contribution to effects of HDACi on hepatocellular carcinoma. Cell Cycle.
• Merchant, J. (2012). Plasma Shh levels reduced in pancreatic cancer patients. Pancreas.
• Merchant, J. (2012). The same pocket in menin binds both MLL and JUND but has opposite effects on transcription. Nature.
• Merchant, J. (2012). Transgenic expression of interferon-γ in mouse stomach leads to inflammation, metaplasia, and dysplasia. American Journal of Pathology.
• Merchant, J. L. (2012). Abstract PL02-02: Helicobacter gastritis, metaplasia, and gastric cancer. Cancer Prevention Research, 5(11 Supplement), PL02-02-PL02-02. doi:10.1158/1940-6207.prev-12-pl02-02
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  Helicobacter pylori is one of the primary reasons that the gastric epithelium becomes chronically inflamed. As with other epithelial tissues, chronic inflammation can lead to hyperproliferation, metaplasia and eventually gastric cancer. The hedgehog (Hh) pathway is required for embryonic development including development of the gastrointestinal tract. In the pancreas, Hh signaling is extinguished after birth but becomes re-activated by chronic inflammation and when sustained contributes to pancreatic cancer. However, the contribution of Hh signaling in gastric cancer has been less clear. Components of the Hh pathway are elevated in human gastric cancer cell lines, and on this basis, its contribution to gastric cancers have been implicated. Unlike the pancreas, the gastric corpus produces abundant amounts of the Sonic Hedgehog (Shh) ligand. Recent studies have indicated that Shh expressed in the acid-producing parietal cells is required to recruit myeloid cells to the stomach during the initial phase of a Helicobacter infection. We will present evidence showing that the canonical Hh target gene Gli1 is required for the Helicobacter -induced inflammatory response as well as the subsequent development of mucous cell metaplasia, a pre-neoplastic lesion in the stomach. Citation Format: Juanita L. Merchant. Helicobacter gastritis, metaplasia, and gastric cancer. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr PL02-02.
• Saqui-Salces, M., Dowdle, W. E., Reiter, J. F., & Merchant, J. L. (2012). A high-fat diet regulates gastrin and acid secretion through primary cilia. FASEB JOURNAL, 26(8), 3127-3139.
• Saqui-salces, M., & Merchant, J. L. (2012). Primary cilia participate in the gastric endocrine response to food. Regulatory Peptides, 177, S31. doi:10.1016/j.regpep.2012.05.069
• Saqui-salces, M., & Merchant, J. L. (2012). Tu1833 Ingestion of a High Fat Diet Sensed by Primary Cilia Lowers Gastrin Secretion. Gastroenterology, 142(5), S-857. doi:10.1016/s0016-5085(12)63320-4
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  Background:We have recently demonstrated that the presentation of primary cilia on gastric endocrine cells is regulated by food intake. A cilia-deficient mousemodel resulted in increased gastrin mRNA and hypergastrinemia, suggesting the presence of cilia is tightly linked to gastrin production. It has been shown in different organs that cilia dysfunction results in loss of sensory signaling, and obesity is characteristic of two ciliopathies, Bardet-Biedl syndrome and Alstrom. Therefore we tested the hypothesis that antral cilia can discriminate between standard and high fat diets. Methods: We analyzed C57BL/6J mice (wild type) fed with standard (Control, Lab Diet 5L0D) or High Fat (Research Diets Inc., D12492) chow. Mice were starved overnight and then allowed free access to food for 0.5, 1, 1.5, 2, 4 h and overnight (16 h). The amount of food ingested and emptied was determined by weighing the stomachs at time of euthanasia. Gastric acidity was measured by titration of gastric content and gastrin levels by ELISA. Cilia were visualized by immunohistochemistry for acetylated-tubulin then the number of cilia per gland (cpg) was quantified by morphometric analysis. Results: In mice fed Control chow (n=8), the maximum amount of food ingested was achieved by 1 h, gastric contents decreased by 4 h, and gastric acidity peaked at 2 h. The number of antral cilia decreased 45% over 1.5 h and then recovered by 4 h (Fig. 1A). Maximum circulating gastrin levels (3.5 fold increase) occurred by 2 h (Fig.1B). The stomach content, gastric acidity, gastrin levels, and cilia numbers did not change after 4 h of food intake. When mice were fed High Fat chow (n=6), the maximum amount of food ingested was achieved by 1 h and did not decrease for the entire 16 h of the experiment. Gastric acidity increased with High Fat intake, but in contrast with Control chow, remained elevated. The number of antral cilia varied slightly by 2 h then decreased only after 4 h (Fig.1A). Plasma gastrin levels increased 2 fold with High Fat during the first hour (Fig. 1B). However, gastrin levels did not increase further and did not reach the same level than with Control chow. Gastrin levels inversely correlated with antral cilia numbers with both chow diets. The number of cilia in the corpus was not different between the two diets. Conclusion: A high fat diet sensed by cilia on antral endocrine cells regulates gastrin release and thus the gastric response to food intake including acid secretion.
• Saqui-salces, M., Dowdle, W. E., Reiter, J. F., & Merchant, J. L. (2012). 201 Food Intake Stimulates Gastrin and Acid Secretion Through Primary Cilia. Gastroenterology, 142(5), S-49-S-50. doi:10.1016/s0016-5085(12)60190-5
• Syu, L., El-Zaatari, M., Eaton, K. A., Liu, Z., Tetarbe, M., Keeley, T. M., Pero, J., Ferris, J., Wilbert, D., Kaatz, A., Zheng, X., Qiao, X., Grachtchouk, M., Gumucio, D. L., Merchant, J. L., Samuelson, L. C., & Dlugosz, A. A. (2012). Transgenic Expression of Interferon-gamma in Mouse Stomach Leads to Inflammation, Metaplasia, and Dysplasia. AMERICAN JOURNAL OF PATHOLOGY, 181(6), 2114-2125.
• El-zaatari, M., Daignault, S., Anderson, M. A., Plonka, C. M., & Merchant, J. L. (2011). Baseline Levels of Plasma Sonic Hedgehog Vary Widely but Are Reduced in Subjects With Pancreatic Cancer. Gastroenterology, 140(5), S-854. doi:10.1016/s0016-5085(11)63546-4
• El-zaatari, M., Kao, J. Y., Waghray, M., Gumucio, D. L., & Merchant, J. L. (2011). Reduced Hedgehog Signal Transduction Exacerbates the TH1 Response in Helicobacter felis-Infected Mice. Gastroenterology, 140(5), S-86. doi:10.1016/s0016-5085(11)60350-8
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  Background: Helicobacter pylori-induced immune responses are skewed toward the T helper (Th) 1 phenotype, which is indicated by the predominant production of interferon (IFN)γ and tumor necrosis factor (TNF)-α. Toll-like receptors (TLRs) play an essential role in the defense against microbes through the recognition of bacterial molecules. Among TLRs, TLR9 identifies unmethylated CpG DNA sites, which are abundant in bacterial and viral DNA. Although TLR9 signaling exerts pro-inflammatory actions through Th1 responses, the activation of an anti-inflammatory program has been reported in several models of experimental colitis. Aim: To investigate the expression and role of TLR9 in H. pylori-induced gastritis in mice. Methods: Wild-type and TLR9-/mice were inoculated with H. pylori (SS 1 strain). After 2, 4, and 6 months of inoculation of H. pylori, gastric tissues were subjected to activity measurement of myeloperoxidase, a marker of neutrophil infiltration; detection of cytokine mRNA levels by real-time reverse transcriptase-polymerase chain reaction (RTPCR); and immunohistochemical analysis. Results: TLR9 mRNA expression was increased by 6.0-fold, 10.1-fold, and 23.4-fold, respectively, after 2, 4, and 6 months of H. pylori infection. After 2 months, mRNA levels for IFN-γ and TNF-α (Th1-type cytokines) in TLR9-/mice were significantly elevated by 6.7-fold and 5.3-fold, respectively, with a 2.7-fold increase in myeloperoxidase activity, compared to those in H. pylori-infected wild-type mice. The expression of Th1-type cytokines and myeloperoxidase activity in TLR9-/mice were also increased 4 months after H. pylori infection, but these inflammatory parameters were similar 6 months after H. pylori infection in the wild-type and TLR9-/mice. IL-4 and IL-5 (Th2type cytokines) mRNA expression levels did not differ between wild-type and TLR9-/mice throughout the experiment. Immunohistochemical analysis showed that TLR9 proteins were mainly expressed on inflammatory cells. Conclusion: These findings suggest that TLR9 signaling may play important roles in the inhibition of H. pylori-induced gastritis in the early phase through the suppression of Th1 differentiation.
• Grasberger, H., & Merchant, J. L. (2011). Deficiency in Dual Oxidases Mitigates Intestinal Inflammatory Response in Acute Salmonella Typhimurium Infection. Gastroenterology, 140(5), S-30. doi:10.1016/s0016-5085(11)60114-5
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  Background: Recent seminal studies in Drosophila showed that H 2 O 2 release by the dual NADPH oxidase (DUOX) is vital for gut epithelial barrier defense and immune homeostasis.We previously showed that DUOX is only functional as a heterodimer with other transmembrane proteins called dual oxidase maturation factors (DUOXA).In human intestinal epithelial cells, overexpression of DUOX2/DUOXA2 protects against cytoinvasion by intracellular pathogens, and enhances NOD2-initiated signaling and IL-8 production, whereas DUOX2 knockdown has the opposite effect.Evolutionary conservation and high expression levels in barrier epithelia point to an important role of the DUOX system in gut innate immunity of higher vertebrates, but this hypothesis has yet to be tested In Vivo.Aim: To demonstrate an essential role for DUOX in the innate immune response in a novel mouse model.Methods: Complete DUOX inactivation in mice was achieved by simultaneous targeting of the two adjacent Duoxa genes in embryonic stem cells.Duoxa1/Duoxa2 double knockout mice (Duoxa-dKO) do not express functional DUOXA proteins and, hence, functional DUOXbased NADPH oxidase complexes.10-12 week old wildtype (wt) and Duoxa-dKO on a pure 129S6 genetic background were pretreated with streptomycin followed by oral gavage with 10 7 cfu Salmonella Typhimurium (aroA-).Results: S. Typhimurium infection induced Duox2 and Duoxa2 mRNA and protein in the ceca of wt mice.At 24 hours post infection, Duoxa2 mRNA was almost 30-fold higher compared to uninfected streptomycin pretreated controls.At 72 hours post infection, wt animals (n=8) displayed the hallmarks of profound cecal inflammation.In contrast, the ceca of infected Duoxa-dKO mice (n=5) were less shrunken, showed less disruption of crypt organization and submucosal edema, and less epithelial erosions and goblet cell loss.The reduced neutrophil infiltration in the ceca of Duoxa-dKO was correlated with lower tissue myeloperoxidase activity (0.07 vs 0.17 U/mg protein; p= 0.03).Loss of functional Duox also diminished induction of the mRNA for KC chemokine, a murine equivalent of human IL-8, in the colon of infected mice (58% of the level in wt mice; p=0.06).Colonization of ceca and midcolons with Salmonella did not differ between Duoxa-dKO and wt mice, but ileal colonization was ~10 fold higher in Duoxa-dKO.Conclusion: This study provides the first In Vivo evidence for an important role of DUOX in gut innate immunity of higher vertebrates.Loss of DUOX activity mitigates the acute inflammatory host response to Salmonella infection despite normal or even increased intestinal colonization.These results raise the possibility that DUOX generated H 2 O 2 not only functions as a direct effector on luminal bacteria, but also plays a more intricate role in inflammatory epithelial signaling.
• Grasberger, H., Chang, L., Shih, W., Presson, A. P., Mayer, E. A., Conyers, F., & Merchant, J. L. (2011). A Functional Promoter Variant in the Tryptophan Hydroxylase 1 Gene is Associated With a Bowel Habit Phenotype in Patients With Irritable Bowel Syndrome (IBS). Gastroenterology, 140(5), S-111. doi:10.1016/s0016-5085(11)60450-2
• Grasberger, H., Conyers, F., & Merchant, J. L. (2011). EGR-1 Binds a Common Proximal Promoter SNP and Mediates Allele-Specific Differences in TPH1 Promoter Activity. Gastroenterology, 140(5), S-630-S-631. doi:10.1016/s0016-5085(11)62607-3
• Grasberger, H., Saqui-salces, M., El-zaatari, M., Tessier, A., Hayes, M. M., & Merchant, J. L. (2011). Transcription Factor ZBP-89 is Required for Tryptophan Hydroxylase 1 Gene Expression and Serotonin Production. Gastroenterology, 140(5), S-480-S-481. doi:10.1016/s0016-5085(11)61981-1
• Merchant, J. (2011). Gastric tuft cells express DCLK1 and are expanded in hyperplasia. Histochemistry and Cell Biology.
• Merchant, J. (2011). Menin and JunD regulate gastrin gene expression through proximal DNA elements. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2011). ZBP-89 enhances Bak expression and causes apoptosis in hepatocellular carcinoma cells. Biochimica et Biophysica Acta - Molecular Cell Research.
• Qiao, X. T., Samuelson, L. C., Merchant, J. L., Gumucio, D. L., & Dlugosz, A. A. (2011). Villin-Marked Gastric Epithelial Progenitor Cells Do Not Give Rise to Tumors or Metaplastic Cells in a Variety of Mouse Models. Gastroenterology, 140(5), S-830. doi:10.1016/s0016-5085(11)63439-2
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  following tamoxifen induction.Once again, lineage tracing of all the epithelial cells within marked glands was observed up to 52 weeks following tamoxifen induction, suggesting that K19 likely marks a common progenitor or stem cell in the antrum, intestine and colon.Interestingly, in the small intestine and antrum K19 positive cells do not overlap with Lgr5-GFP+ cells yet clearly demonstrate stem cell properties.Conclusions.Using K19CreERT2/ Rosa26r mice, we show that K19 marks pit progenitors in the gastric corpus, as well as stem cells within the antrum, intestine and colon.These findings identify a novel population of stem cells for the lineage tracing of gastric pit cells following gastric injury or cancer, and for tracing epithelial cells in the development of intestinal or colonic cancer.
• Saqui-salces, M., & Merchant, J. L. (2011). Differential Response of Primary Cilia to Food and Distension in the Gastric Corpus and Antrum. Gastroenterology, 140(5), S-323. doi:10.1016/s0016-5085(11)61310-3
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  20.02±5.16)much higher than perilla oil alone did .Other lipids also potentiated GLP-2 secretion significantly when administered with a sweetener.Conclusions : Effect on GLP-2 secretion differs among a variety of lipids.A sweetener may did not have capability to induce GLP-2 secretion alone but has synergistic effect by the combination of dietary lipids and a sweetener on GLP-2 secretion.The potential effects by sugar, sweetener, and lipids may be physiologically important and these information will give us a new strategy for nutritional therapy for intestinal disorders.
• Saqui-salces, M., Dowdle, W. E., Reiter, J. F., & Merchant, J. L. (2011). Disruption of Primary Cilia Induces Gastric Mucosal Hyperplasia. Gastroenterology, 140(5), S-93. doi:10.1016/s0016-5085(11)60378-8
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  BACKGROUND: Primary cilia are necessary for Hedgehog (Hh) signaling and other pathways. Anterograde ciliary transport is mediated by kinesin-II, a heterotrimeric protein composed of two motor subunits, KIF3A, KIF3B, and a non-motor subunit KAP3. Intraflagellar transport protein 88 (IFT88) participates in protein transport along the cilia. Conventional null mice for KIF3A and IFT88 are not viable. Sonic hedgehog (Shh) is highly expressed in gastric epithelial cells of the corpus compared to the antrum. Therefore we examined the stomach of mice conditionally null for KIF3A and IFT88 to define the role of primary cilia in this organ. METHODS: KIF3A and IFT88 mice harboring one null allele and loxP sites on the other allele on a ROSA26 reporter background were crossed to Shh-Cre mice (KIF3A-/ FL and IFT88-/FL respectively.) KIF3A+/FL, IFT88+/FL, and wild type (WT) littermates were analyzed at 6 and 8 months. Cell lineages were identified by immunohistochemistry in paraffin-sections, and by β-galactosidase (β-gal) staining for the Cre-expressing cells. Acetylated-α-tubulin was used as the marker for cilia. RESULTS: Epithelial cells in the antrum and corpus expressed primary cilia. β-gal staining confirmed variegated glandular Cre expression in all epithelial cells. Gastric epithelial cells did not express cilia in the IFT88-/FL mice, while KIF3A-/FL mice showed reduced numbers of cilia in the corpus versus controls (0.59+0.04 cilia/gland, N=8 vs. 0.72+0.06 cilia/gland, N=14), but no changes in the antrum (0.94+0.05 vs. 1.08+0.09 cilia/gland.) KIF3A-/FL and IFT88-/FL mice exhibited different phenotypes. By 6 months, KIF3A-/FL mice showed mucous pit hyperplasia in the corpus. Mucous neck and zymogenic lineages were not expanded, but parietal cells were still present. The KIF3A-/FL mice phenotype resembled the mucous pit hyperplasia observed in the Shh conditionally null mice generated with H+K+ATPase-Cre. In contrast, the phenotype of the IFT88-/FL mice showed parietal cell atrophy, and proximal corpus hyperplasia due to expansion of the mucous neck cell compartment assessed by TFF2 expression (SPEM) by 4 months of age. We have previously observed that gastrinand ghrelin-secreting cells exhibit primary cilia, but none of the mouse models showed differences in the number of these endocrine cells.CONCLUSION:The IFT88-/FLmice exhibited amore severe phenotype than the KIF3A-/FL mice even though both molecules affect primary cilia function. The phenotype of these two mouse models suggests that Hh signaling is necessary for the maintenance of the corpus epithelium. Also, gastric epithelial cilia might be important for the function but not differentiation of gastrinand ghrelin-secreting cells.
• Saqui-salces, M., Dowdle, W. E., Reiter, J. F., & Merchant, J. L. (2011). Mice With Gastric Hyperplasia Develop Obesity, Fatty Liver and Large Pancreatic Islets. Gastroenterology, 140(5), S-332. doi:10.1016/s0016-5085(11)61349-8
• Saqui-salces, M., Keeley, T. M., Samuelson, L. C., Gumucio, D. L., & Merchant, J. L. (2011). Gastro-Intestinal Tuft Cells Are DCLK1 Positive, and Appear Late in Development. Gastroenterology, 140(5), S-148. doi:10.1016/s0016-5085(11)60601-x
• Saqui-salces, M., Waghray, M., Merchant, J. L., Coves-datson, E. M., & Dlugosz, A. A. (2011). Induction of Follistatin in Metaplastic Antra of Gastrin Null Mice Correlates With Increased Hedgehog Signaling. Gastroenterology, 140(5), S-92. doi:10.1016/s0016-5085(11)60375-2
• Veniaminova, N. A., & Merchant, J. L. (2011). Loss of Menin Results in Hypergastrinemia Originating From Antral G Cells. Gastroenterology, 140(5), S-630. doi:10.1016/s0016-5085(11)62606-1
• Grasberger, H., El-zaatari, M., Tessier, A., Merchant, J. L., Hayes, M. M., & Veniaminova, N. A. (2010). Transcription factor ZBP-89 is required for tryptophanhydroxylase 1 gene expression and serotonin production.. Regulatory Peptides, 164(1), 29. doi:10.1016/j.regpep.2010.07.066
• Kao, J. Y., Liu, M., Zhang, M., Waghray, M., Tessier, A., Bai, L., Merchant, J. L., & Zaatari, M. E. (2010). 265 Loss of Hedgehog Signaling Enhances Helicobacter Immune Escape. Gastroenterology, 138(5), S-49. doi:10.1016/s0016-5085(10)60223-5
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  these cytokines in WT mice, but not in iNOS -/-mice.DFMO treatment caused an increase in Th2 cytokines (IL-4, IL-13) and Treg (IL-10) cytokine protein levels in WT mice, but not in iNOS -/-mice.In WT mice reconstituted with iNOS -/-bone marrow, DFMO treatment failed to reduce Hp colonization and gastritis, whereas in iNOS -/-mice reconstituted with WT bone marrow, attenuation of Hp colonization and gastritis with DFMO was restored (Table ).Conclusions: Induction of ODC during Hp infection impairs immune responses required for antimicrobial activity that are mediated by NO.As such, polyamines contribute to the persistence of Hp infection and severity of gastritis.n = 5 -10 per group; *p < 0.05 vs WT/WT -DFMO; §p < 0.05, § §p < 0.01 vs WT/WT + DFMO; †p < 0.05 vs iNOS -/-/iNOS -/-+ DFMO; ##p < 0.01 vs iNOS -/-/WT + DFMO.
• Merchant, J. (2010). Bone morphogenetic protein signaling regulates gastric epithelial cell development and proliferation in mice. Gastroenterology.
• Merchant, J. (2010). Clogged up. Efforts to train more minority doctors remain stalled as population diversifies.. Modern healthcare.
• Merchant, J. (2010). Hedgehog Is an Anti-Inflammatory Epithelial Signal for the Intestinal Lamina Propria. Gastroenterology.
• Merchant, J. (2010). Hedgehog signaling and gastrointestinal cancer. Biochimica et Biophysica Acta - Molecular Cell Research.
• Merchant, J. (2010). Helicobacter pylori induction of the gastrin promoter through GC-rich DNA elements. Helicobacter.
• Merchant, J. (2010). Interleukin-1β Promotes Gastric Atrophy Through Suppression of Sonic Hedgehog. Gastroenterology.
• Merchant, J. (2010). Intracellular calcium release and protein kinase c activation stimulate sonic hedgehog gene expression during gastric acid secretion. Gastroenterology.
• Merchant, J. (2010). Reply. Gastroenterology.
• Merchant, J. (2010). Underrepresentation of Underrepresented Minorities in Academic Medicine: The Need to Enhance the Pipeline and the Pipe. Gastroenterology.
• Merchant, J. L., & Omary, M. B. (2010). Underrepresentation of Underrepresented Minorities in Academic Medicine: The Need to Enhance the Pipeline and the Pipe. GASTROENTEROLOGY, 138(1), 19-26.
• Merchant, J. L., & Veniaminova, N. A. (2010). S1696 Menin Inhibits Gastrin Gene Expression via Cooperation With JunD and SP1. Gastroenterology, 138(5), S-255. doi:10.1016/s0016-5085(10)61166-3
• Saqui-Salces, M., & Merchant, J. L. (2010). Hedgehog signaling and gastrointestinal cancer. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH, 1803(7), 786-795.
• Saqui-salces, M., Hayes, M. M., Hockeimer, W. D., Merchant, J. L., Veniaminova, N. A., & Zaatari, M. E. (2010). 726 Colocalization of Atm and ZBP-89 to Enterochromaffin Cells. Gastroenterology, 138(5), S-98. doi:10.1016/s0016-5085(10)60447-7
• Saqui-salces, M., Merchant, J. L., & Veniaminova, N. A. (2010). 960 Disheveled Inhibits ZBP-89 Activation of p21Wa and OLFM4, an Intestinal Notch Target. Gastroenterology, 138(5), S-140. doi:10.1016/s0016-5085(10)60644-0
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  or PTEN, suggesting that NFAT5 regulates signaling events that directly control Akt phosphorylation at Ser473 site.Interestingly, knockdown of NFAT5 decreased the interaction between Akt and PHLPP.These results suggest that NFAT5 may regulate Akt (Ser473) phosphorylation through altering PHLPP-mediated inhibition of Akt.CONCLUSIONS.Our results demonstrate a role of NFAT5 in intestinal cell differentiation.Importantly, these data suggest that NFAT5-dependent positive regulation of differentiation is mediated by negatively affecting Akt phosphorylation through the novel regulation of the interaction between PHLPP and Akt.
• Shinohara, M., Mao, M., Keeley, T. M., El-Zaatari, M., Lee, H., Eaton, K. A., Samuelson, L. C., Merchant, J. L., Goldenring, J. R., & Todisco, A. (2010). Bone Morphogenetic Protein Signaling Regulates Gastric Epithelial Cell Development and Proliferation in Mice. GASTROENTEROLOGY, 139(6), 2050-U349.
• Shinohara, M., Mao, M., Keeley, T. M., Elzaatari, M., Lee, H., Eaton, K. A., Samuelson, L. C., Merchant, J. L., Goldenring, J. R., & Todisco, A. (2010). Bone morphogenetic protein signaling regulates gastric epithelial cell development and proliferation in mice. Gastroenterology, 139(Issue 6). doi:10.1053/j.gastro.2010.08.052
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  Background & Aims We investigated the role of bone morphogenetic protein (BMP) signaling in the regulation of gastric epithelial cell growth and differentiation by generating transgenic mice that express the BMP inhibitor noggin in the stomach. Methods The promoter of the mouse H+/K+-ATPase β-subunit gene, which is specifically expressed in parietal cells, was used to regulate expression of noggin in the gastric epithelium of mice. The transgenic mice were analyzed for noggin expression, tissue morphology, cellular composition of the gastric mucosa, gastric acid content, and plasma levels of gastrin. Tissues were analyzed by immunohistochemical, quantitative real-time polymerase chain reaction, immunoblot, microtitration, and radioimmunoassay analyses. Results In the stomachs of the transgenic mice, phosphorylation of Smad 1, 5, and 8 decreased, indicating inhibition of BMP signaling. Mucosa were of increased height, with dilated glands, cystic structures, reduced numbers of parietal cells, and increased numbers of cells that coexpressed intrinsic factor, trefoil factor 2, and Griffonia (Bandeiraea) simplicifolia lectin II, compared with wild-type mice. In the transgenic mice, levels of the H+/K+-ATPase α-subunit protein and messenger RNA were reduced, whereas those of intrinsic factor increased. The transgenic mice were hypochloridric and had an increased number of Ki67- and proliferating cell nuclear antigen-positive cells; increased levels of plasma gastrin; increased expression of transforming growth factor-α, amphiregulin, and gastrin; and activation of extracellular signal-regulated kinase 2. Conclusions Inhibiting BMP signaling in the stomachs of mice by expression of noggin causes loss of parietal cells, development of transitional cells that express markers of mucus neck and zymogenic lineages, and activation of proliferation. BMPs are therefore important regulators of gastric epithelial cell homeostasis. © 2010 AGA Institute.
• Waghray, M., Zavros, Y., Saqui-Salces, M., El-Zaatari, M., Alamelumangapuram, C. B., Todisco, A., Eaton, K. A., & Merchant, J. L. (2010). Interleukin-1 beta Promotes Gastric Atrophy Through Suppression of Sonic Hedgehog. GASTROENTEROLOGY, 138(2), 562-U202.
• Waghray, M., Zavros, Y., Saqui-Salces, M., El-Zaatari, M., Alamelumangapuram, C. B., Todisco, A., Eaton, K. A., & Merchant, J. L. (2010). Interleukin-1β Promotes Gastric Atrophy Through Suppression of Sonic Hedgehog. Gastroenterology, 138(Issue 2). doi:10.1053/j.gastro.2009.10.043
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  Background & Aims: In both human subjects and rodent models, Helicobacter infection leads to a decrease in Shh expression in the stomach. Sonic Hedgehog (Shh) is highly expressed in the gastric corpus and its loss correlates with gastric atrophy. Therefore, we tested the hypothesis that proinflammatory cytokines induce gastric atrophy by inhibiting Shh expression. Methods: Shh-LacZ reporter mice were infected with Helicobacter felis for 3 and 8 weeks. Changes in Shh expression were monitored using β-galactosidase staining and immunohistochemistry. Gastric acidity was measured after infection, and interleukin (IL)-1β was quantified by quantitative reverse-transcription polymerase chain reaction. Mice were injected with either IL-1β or omeprazole before measuring Shh mRNA expression and acid secretion. Organ cultures of gastric glands from wild-type or IL-1R1 null mice were treated with IL-1β then Shh expression was measured. Primary canine parietal or mucous cells were treated with IL-1β. Shh protein was determined by immunoblot analysis. Changes in intracellular calcium were measured by Fura-2. Results: All major cell lineages of the corpus including surface pit, mucous neck, zymogenic, and parietal cells expressed Shh. Helicobacter infection reduced gastric acidity and inhibited Shh expression in parietal cells by 3 weeks. IL-1β produced during Helicobacter infection inhibited gastric acid, intracellular calcium, and Shh expression through the IL-1 receptor. Suppression of parietal cell Shh expression by IL-1β and omeprazole was additive. IL-1β did not suppress Shh expression in primary gastric mucous cells. Conclusions: IL-1β suppresses Shh gene expression in parietal cells by inhibiting acid secretion and subsequently the release of intracellular calcium. © 2010 AGA Institute.
• Zacharias, W. J., Li, X., Madison, B. B., Kretovich, K., Kao, J. Y., Merchant, J. L., & Gumucio, D. L. (2010). Hedgehog Is an Anti-Inflammatory Epithelial Signal for the Intestinal Lamina Propria. GASTROENTEROLOGY, 138(7), 2368-U226.
• Zavros, Y., Waghray, M., Todisco, A., Shulkes, A., Merchant, J. L., & Mesiwala, N. K. (2010). Histamine 3 receptor activation mediates inhibition of acid secretion during Helicobacter-induced gastritis.. World journal of gastrointestinal pathophysiology, 1(5), 154-65. doi:10.4291/wjgp.v1.i5.154
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  To test the hypothesis that histamine 3 receptor (H3R) activation during Helicobacter infection inhibits gastric acid secretion in vivo and in vitro..Helicobacter felis (H. felis) infected and uninfected C57Bl/6 mice were infused with either PBS or the H3 receptor antagonist thioperamide (THIO) for 12 wk. After treatment, mice were analyzed for morphological changes and gastric acid content. Total RNA was prepared from the stomachs of each group and analyzed for changes in somatostatin and gastrin mRNA abundance by real time-polymerase chain reaction (RT-PCR). Location of H3 receptors in the stomach was analyzed by co-localization using antibodies specific for the H3 receptor and parietal cell marker H(+), K(+)-ATPase β subunit..Inflammation and parietal cell atrophy was observed after 12 wk of H. felis infection. Interestingly, treatment with the H3R antagonist thioperamide (THIO) prior to and during infection prevented H. felis-induced inflammation and atrophy. Compared to the uninfected controls, infected mice also had significantly decreased gastric acid. After eradication of H. felis with THIO treatment, gastric acidity was restored. Compared to the control mice, somatostatin mRNA abundance was decreased while gastrin gene expression was elevated during infection. Despite elevated gastric acid levels, after eradication of H. felis with THIO, somatostatin mRNA was elevated whereas gastrin mRNA was suppressed. Immunofluorescence revealed the presence of H3 receptors on the parietal cells, somatostatin-secreting D-cells as well as the inflammatory cells..This study shows that during H. felis infection, gastric acidity is suppressed as a consequence of an inhibitory effect on the parietal cell by H3R activation. The stimulation of gastric mucosal H3Rs increases gastrin expression and release by inhibiting release of somatostatin.
• Kolterud, A., Kolterud, A., Grosse, A. S., Grosse, A. S., Zacharias, W. J., Zacharias, W. J., Walton, K. D., Walton, K. D., Kretovich, K. E., Kretovich, K. E., Madison, B. B., Madison, B. B., Waghray, M., Waghray, M., Ferris, J. E., Ferris, J. E., Hu, C., Hu, C., Merchant, J. L., , Merchant, J. L., et al. (2009). Paracrine Hedgehog Signaling in Stomach and Intestine: New Roles for Hedgehog in Gastrointestinal Patterning. GASTROENTEROLOGY, 137(2), 618-628.
• Merchant, J. (2009). Paracrine Hedgehog Signaling in Stomach and Intestine: New Roles for Hedgehog in Gastrointestinal Patterning. Gastroenterology.
• Merchant, J. (2009). Sonic hedgehog in gastric physiology and neoplastic transformation: Friend or foe?. Current Opinion in Endocrinology, Diabetes and Obesity.
• Merchant, J. (2009). ZBP-89 reduces the cell death threshold in hepatocellular carcinoma cells by increasing caspase-6 and S phase cell cycle arrest. Cancer Letters.
• Saqui-salces, M., & Merchant, J. L. (2009). M1619 Gastric Epithelial Cells Express Primary Cilia. Gastroenterology, 136(5), A-396. doi:10.1016/s0016-5085(09)61818-7
• Saqui-salces, M., & Merchant, J. L. (2009). M1643 IL-1β Induces Specific Gastric Mucous Cell Differentiation and Proliferation. Gastroenterology, 136(5), A-401. doi:10.1016/s0016-5085(09)61842-4
• Saqui-salces, M., Waghray, M., Tessier, A., Bai, L., Merchant, J. L., & Zaatari, M. E. (2009). 866 Sonic Hedgehog Regulates Mucous Neck to Zymogenic Cell Lineage Specification. Gastroenterology, 136(5), A-133. doi:10.1016/s0016-5085(09)60595-3
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  study investigated the cellular basis of the mesenchymal expansion and the possible involvement of Hedgehog signaling.METHODS: Vil-Math1 transgenic founder intestines were examined at embryonic day E18.5 by immunohistochemistry and quantitative RT-PCR to follow changes in cell fate, proliferation, and expression of Hedgehog pathway genes.RESULTS: Mesenchymal cell proliferation was increased in Vil-Math1 transgenics, consistent with a proportional increase in tissue area from 30% to 50%.Accordingly, expression of the general mesenchyme marker vimentin was increased up to 3.6-fold.Co-immunostaining with desmin and α-smooth muscle actin showed that smooth muscle precursors, myofibroblasts, and differentiated smooth muscle were expanded in Vil-Math1 transgenics, roughly corresponding to Math1 transgenic expression and epithelial cell remodeling.Immunostaining for neurofilament demonstrated that enteric neurons were also expanded.Although many mesenchymal cell types were expanded, radial tissue patterning was maintained.We tested expression of Hedgehog signaling components since Hedgehog KO mice have phenotypes complimentary to Vil-Math1 transgenics (loss of smooth muscle and enteric neurons).Hedgehog ligands are normally expressed in the epithelium and signal in a paracrine fashion to the mesenchyme.Vil-Math1 transgenics had increased expression of both Indian and Sonic Hedgehog (up to 3.3-and 3.6-fold, respectively), despite reduction in epithelial area.In addition, there was increased expression of Hedgehog transcriptional targets, including Gli1 (up to 2.3-fold) and Ptch1 (up to 2.7-fold).CONCLUSIONS: Vil-Math1 transgenics exhibited a general mesenchymal hyperplasia with normal radial patterning and had increased expression of Hedgehog pathway components.This study revealed a novel function of Math1 as a regulator of crosstalk between the intestinal epithelium and mesenchyme and suggests that Hedgehog signaling is altered in response to the cellular changes induced by Math1.
• Jain, R. N., Al-Menhaii, A. A., Keeley, T. M., Ren, J., EI-Zaatari, M., Chen, X., Merchant, J. L., Ross, T. S., Chew, C. S., & Samuelson, L. C. (2008). Hip1r is expressed in gastric parietal cells and is required for tubulovesicle formation and cell survival in mice. JOURNAL OF CLINICAL INVESTIGATION, 118(7), 2459-2470.
• Merchant, J. (2008). Gastrin transactivates the chromogranin A gene through MEK-1/ERK- and PKC-dependent phosphorylation of Sp1 and CREB. Cellular Signalling.
• Merchant, J. (2008). Hip 1r is expressed in gastric parietal cells and is required for tubulovesicle formation and cell survival in mice. Journal of Clinical Investigation.
• Merchant, J. (2008). Induction of follistatin precedes gastric transformation in gastrin deficient mice. Biochemical and Biophysical Research Communications.
• Merchant, J. (2008). Regulated expression of the human gastrin gene in mice. Regulatory Peptides.
• Merchant, J. (2008). Somatostatin stimulates menin gene expression by inhibiting protein kinase A. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2008). Tissue stem cells and cancer stem cells: Potential implications for gastric cancer. Panminerva Medica.
• Merchant, J. (2008). What lurks beneath: IL-11, via Stat3, promotes inflammation-associated gastric tumorigenesis. Journal of Clinical Investigation.
• Merchant, J. L., & Mensah-osman, E. J. (2008). 814 Octreotide Stimulates Menin in Somatostatin-Expressing Cells of the Duodenum. Gastroenterology, 134(4), A-115-A-116. doi:10.1016/s0016-5085(08)60539-9
• Shinohara, M., Mao, M. Y., Keeley, T. M., Eaton, K. A., Samuelson, L. C., Merchant, J. L., Todisco, A., & Zaatari, M. E. (2008). 815 Physiological Significance of Bone Morphogenetic Protein (BMP) Signaling in the Stomach. Gastroenterology, 134(4), A-116. doi:10.1016/s0016-5085(08)60540-5
• Waghray, M., & Merchant, J. L. (2008). S1604 Helicobacter felis Infection Modulates Gastric Sonic Hedgehog Expression and Signaling. Gastroenterology, 134(4), A-233. doi:10.1016/s0016-5085(08)61075-6
• Bai, L., & Merchant, J. L. (2007). Role for CITED2, a CBP/p300 interacting protein, in colon cancer cell invasion. FEBS LETTERS, 581(30), 5904-5910.
• Chupreta, S., Brevig, H., Bai, L., Merchant, J. L., & Iniguez-Lluhi, J. A. (2007). Sumoylation-dependent control of homotypic and heterotypic synergy by the kruppel-type zinc finger protein ZBP-89. JOURNAL OF BIOLOGICAL CHEMISTRY, 282(50), 36155-36166.
• Merchant, J. (2007). A role for CITED2, a CBP/p300 interacting protein, in colon cancer cell invasion. FEBS Letters.
• Merchant, J. (2007). ATM phosphorylates ZBP-89 at Ser202 to potentiate p21^waf1 induction by butyrate. Biochemical and Biophysical Research Communications.
• Merchant, J. (2007). H pylori infection causes chronic pancreatitis in Mongolian gerbils. World Journal of Gastroenterology.
• Merchant, J. (2007). Prospective Identification of a Multilineage Progenitor in Murine Stomach Epithelium. Gastroenterology.
• Merchant, J. (2007). Re-expression of sonic hedgehog and reduction of CDX2 after Helicobacter pylori eradication prior to incomplete intestinal metaplasia. International Journal of Cancer.
• Merchant, J. (2007). Reduced pepsin A processing of sonic hedgehog in parietal cells precedes gastric atrophy and transformation. Journal of Biological Chemistry.
• Merchant, J. (2007). Sumoylation-dependent control of homotypic and heterotypic synergy by the Krüppel-type zinc finger protein ZBP-89. Journal of Biological Chemistry.
• Merchant, J. (2007). Tales from the crypts: Regulatory peptides and cytokines in gastrointestinal homeostasis and disease. Journal of Clinical Investigation.
• Qiao, X. T., Ziel, J. W., Mckimpson, W., Madison, B. B., Todisco, A., Merchant, J. L., Samuelson, L. C., & Gumucio, D. L. (2007). Prospective identification of a multilineage progenitor in murine stomach epithelium. GASTROENTEROLOGY, 133(6), 1989-1998.
• Shiotani, A., Uedo, N., Iishi, H., Tatsuta, M., Ishiguro, S., Nakae, Y., Kamada, T., Haruma, K., & Merchant, J. L. (2007). Re-expression of sonic hedgehog and reduction of CDX2 after Helicobacter pylori eradication prior to incomplete intestinal metaplasia. INTERNATIONAL JOURNAL OF CANCER, 121(6), 1182-1189.
• Zavros, Y., Waghray, M., Tessier, A., Bai, L., Todisco, A., Gumucio, D. L., Samuelson, L. C., Dlugosz, A., & Merchant, J. L. (2007). Reduced pepsin a processing of sonic hedgehog in parietal cells precedes gastric atrophy and transformation. JOURNAL OF BIOLOGICAL CHEMISTRY, 282(46), 33265-33274.
• Zavros, Y., Waghray, M., Tessier, A., Todisco, A., Gumucio, D. L., Samuelson, L. C., Dlugosz, A. A., & Merchant, J. L. (2007). Sonic hedgehog processing by pepsin A is altered in human gastric cancer. The FASEB Journal, 21(6). doi:10.1096/fasebj.21.6.a1321-b
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  Objective Sonic hedgehog (Shh) function is not only essential to development of the gastrointestinal tract, but also maintains the characteristic acid-secreting phenotype of the adult stomach. Like Shh mutant mice, gastrin null mice display metaplastic changes in the stomach but also develop gastric cancer. Since loss of Shh correlates with gastric atrophy, we examined whether gastrin regulates Shh levels in the acid-secreting parietal cell. Methods Shh processing was studied using canine parietal cells, human normal and tumor stomach extracts and human gastric cell lines (HGT-1, NCI/N87). Results Gastrin treatment of primary parietal cell cultures stimulated processing of the 45 kDa precursor to both the 26 and 19 kDa proteins. This cleavage was blocked by the proton pump inhibitor omeprazole. Pepsin A was confirmed as the protease responsible for processing Shh in whole cell extracts from normal human corpus. In contrast, extracts from human gastric tumors have reduced levels of pepsin A and thus lose the ability to process Shh. As observed with tumor extracts, gastric cell lines without pepsin A activity did not process Shh, but rather maintained elevated levels of the 45 kDa Shh precursor. We found that the 45 kDa precursor was secreted and able to activate hedgehog signaling. Conclusion Therefore processing of Shh in the stomach is hormonally-regulated, acid-dependent and mediated by the protease pepsin A.
• Kao, J. Y., Rathinavelu, S., Eaton, K. A., Bai, L., Zavros, Y., Takami, M., Pierzchala, A., & Merchant, J. L. (2006). Helicobacter pylori-secreted factors inhibit dendritic cell IL-12 secretion: a mechanism of ineffective host defense. AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY, 291(1), G73-G81.
• Law, D. J., Labut, E. M., & Merchant, J. L. (2006). Intestinal overexpression of ZNF148 suppresses Apc(Min)/+ neoplasia. MAMMALIAN GENOME, 17(10), 999-1004.
• Merchant, J. (2006). An isoform of ZBP-89 predisposes the colon to colitis. Nucleic Acids Research.
• Merchant, J. (2006). Helicobacter pylori-induced atrophic gastritis progressing to gastric cancer exhibits sonic hedgehog loss and aberrant CDX2 expression. Alimentary Pharmacology and Therapeutics.
• Merchant, J. (2006). Helicobacter pylori-secreted factors inhibit dendritic cell IL-12 secretion: A mechanism of ineffective host defense. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2006). Identification of zinc finger binding protein 89 (ZBP-89) as a transcriptional activator for a major bovine growth hormone receptor promoter. Molecular and Cellular Endocrinology.
• Merchant, J. (2006). Inhibition of growth hormone receptor gene expression by saturated fatty acids: Role of krüppel-like zinc finger factor, ZBP-89. Molecular Endocrinology.
• Merchant, J. (2006). Intestinal alkaline phosphatase gene expression is activated by ZBP-89. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2006). Intestinal overexpression of ZNF148 suppresses Apc^Min/+ neoplasia. Mammalian Genome.
• Merchant, J. (2006). Parietal cell hyperstimulation and autoimmune gastritis in cholera toxin transgenic mice. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2006). Recruitment of Ataxia-Telangiectasia Mutated to the p21^waf1 Promoter by ZBP-89 Plays a Role in Mucosal Protection. Gastroenterology.
• Merchant, J. (2006). Somatostatin inhibits dendritic cell responsiveness to Helicobacter pylori. Regulatory Peptides.
• Merchant, J. (2006). p53 mutants suppress ZBP-89 function. Anticancer Research.
• Zavros, Y., Zhang, L., & Merchant, J. L. (2006). Sonic hedgehog (Shh) processing in gastric cancer cells is dependent on the activation of pepsinogen. The FASEB Journal, 20(5).
• Merchant, J. (2005). Chronic gastritis in the hypochlorhydric gastrin-deficient mouse progresses to adenocarcinoma. Oncogene.
• Merchant, J. (2005). Epithelial cell turnover in relation to ongoing damage of the gastric mucosa in patients with early gastric cancer: increase of cell proliferation in paramalignant lesions.. Journal of gastroenterology.
• Merchant, J. (2005). Evidence that loss of sonic hedgehog is an indicator of Helicobater pylori-induced atrophic gastritis progressing to gastric cancer. American Journal of Gastroenterology.
• Merchant, J. (2005). Helicobacter pylori cag-type IV secretion system facilitates corpus colonization to induce precancerous conditions in mongolian gerbils. Gastroenterology.
• Merchant, J. (2005). Helicobacter pylori outer membrane protein 18 (Hp1125) induces dendritic cell maturation and function. Helicobacter.
• Merchant, J. (2005). Helicobacter-induced intestinal metaplasia in the stomach correlates with Elk-1 and serum response factor induction of villin. Journal of Biological Chemistry.
• Merchant, J. (2005). Inflammation, atrophy, gastric cancer: Connecting the molecular dots. Gastroenterology.
• Merchant, J. (2005). Interferon gamma induction of gastric mucous neck cell hypertrophy. Laboratory Investigation.
• Merchant, J. (2005). Modulating the cytokine response to treat Helicobacter gastritis. Biochemical Pharmacology.
• Merchant, J. (2005). Regulation and function of the sonic hedgehog signal transduction pathway in isolated gastric parietal cells. Journal of Biological Chemistry.
• Merchant, J. (2005). The Epstein-Barr virus protein BMRF1 activates gastrin transcription. Journal of Virology.
• Merchant, J. L., Shiotani, A., Iishi, H., Ishiguro, S., Tatsuta, M., & Nakae, Y. (2005). Epithelial cell turnover in relation to ongoing damage of the gastric mucosa in patients with early gastric cancer: increase of cell proliferation in paramalignant lesions. Journal of Gastroenterology, 40(4), 337-44. doi:10.1007/s00535-004-1549-9
• Bai, L., & Merchant, J. L. (2004). Erratum: Transcription factor ZBP-89 is required for STAT1 constitutive expression (Nucleic Acids Research (2003) vol. 31 (7264-7270)). Nucleic Acids Research, 32(4), 1615-1615. doi:10.1093/nar/gkh308
• LeVan, T., Lambert, P., Martinez, F., Stromquist, A., Merchant, J., & Von Essen, S. (2004). Single Nucleotide Polymorphisms in the Cd14 Promoter are Associated with Pulmonary Function in Farmers. Journal of Investigative Medicine, 52(2_suppl_part_2), 386-386. doi:10.1177/108155890405202s130
• Merchant, J. (2004). Inflammation and Cancer III. Somatostatin and the innate immune system. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2004). Kinetic profiles of p300 occupancy in vivo predict common of promoter structure and coactivator recruitment. Proceedings of the National Academy of Sciences of the United States of America.
• Merchant, J. (2004). ZBP-89-induced apoptosis is p53-independent and requires JNK. Cell Death and Differentiation.
• Merchant, J. L. (2004). Human molecular biology: By Richard J. Epstein. 656 pp. $150.00. Cambridge University Press, New York, New York, 2003. ISBN 0-521-64285-X. Web address for ordering: www.cambridge.org. Gastroenterology, 126(1), 362-363. doi:10.1053/j.gastro.2003.08.046
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  Richard Epstein takes advantage of his dual training to introduce molecular biology concepts to clinicians that want to understand the basics of human disease in the post-genomics era. The text is a coherent narrative of the evolution of molecular biology that is directly relevant to disease beginning with the “Big Bang” formation of the Universe. Three types of minireviews punctuate each chapter: (1) a molecular minireview; (2) clinical “keynotes” that are essentially the clinical correlations relevant to the prior subsection; and (3) pharmacologic footnotes. A key feature of the text is the seamless integration of clinical disorders with the molecules and pathways known to date that are either mutated or subsequently implicated directly in the disease process or whose levels are modulated so as to implicate signaling pathways. Emphasis is placed on recurring patterns in biology whether one is speaking of cell death (apoptosis), secretion coupling or an antibody response. For example, a molecule or signal is received by a cell and processed depending on the cell and signal type. The specific molecules dealt with in each chapter will be familiar to most (e.g., chromatin, gene expression, integrins, T-cell receptors, cytokines), but are laced together under more intuitive functional categories (e.g., molecular biology to human genetics; molecular genetics to human biochemistry; biochemistry to human cell biology, etc.). This approach favors assimilation of the information by the less “detail-minded” types who will appreciate the focus on the bigger picture. Those that need to use the book purely as a reference source on one specific topic may have difficulty in understanding the information without reading previous chapters. The author makes this clear to the reader in the introduction so that there are no false expectations. This is certainly fair since a textbook cannot be all things to all people. A busy practicing clinician, fellow or resident, will rarely sit down to read a molecular biology textbook from cover to cover. Nevertheless, recent medical school graduates who have had some exposure to molecular biology within the last 10 years should have a relatively easy time extracting the specific information they need without reading the entire text. On the other hand, the practicing clinician will likely be drawn to the clinical keynotes that are usually accompanied by pictures of the related disease entity. For the physician-scientist, scientist, or the merely curious, the book provides an excellent overview of those new areas that you have always heard mentioned, but have never studied in detail. The author enhances the learning of complex pathways with illustrations that capture the essence of the information to be learned without being excessively detailed. A good example of this is the chapter on Development that will certainly be relevant to many gastroenterologists and gastrointestinal physiologists that want to understand the relationship of various developmental pathways to our current understanding of cancer development. The most prominent example of this being the APC pathway. Three features conclude each chapter: a summary, enrichment reading, and quiz questions. As with the Minireview sections, the summaries are succinct and transmit the essence of the chapters in no more than 200 words. The reading list for each chapter is no more than 3 to 6 references grouped according to their purpose. For example, for those wanting to do further reading in a style similar to a short story, the author lists references under the heading “Bedtime reading.” For those wanting a quick paperback type reference, the author designates these references as “Cheap and Cheerful.” Then for the real enthusiast, he directs you to the definitive specialized textbooks on the subject under “Library reference.” For those using the textbook as a teaching text or for students testing their knowledge of the chapter, he provides no more than 10 to 15 “thought” questions at the conclusion of each chapter. Overall, the author achieves his goal of filling a niche for molecular biology textbooks that lucidly integrate the molecular basis of disease with clinical applications. This new text is clearly distinct from most molecular biology textbooks directed toward true students of the field. As most will recall from undergraduate, graduate, or medical school biochemistry, the textbooks tended to teach each subject by drawing from the experiments found in the primary research articles and lessons learned from prokaryotes. This type of approach was probably only palatable for the graduate student already familiar with the field. The textbook of Human Molecular Biology by Richard J. Epstein successfully targets a broader audience with a more a casual interest in the area. Bottom Line: I highly recommend its use as an introductory text for undergraduates and graduate students, as well as clinicians needing a general reference text.
• Bai, L., & Merchant, J. L. (2003). ZBP-89 is required for interferon gamma mediated apoptosis. Gastroenterology, 124(4), A459. doi:10.1016/s0016-5085(03)82320-x
• Kao, J. Y., Rathinavelu, S., & Merchant, J. L. (2003). Somatostatin inhibits LPS-induced dendritic cell maturation. Gastroenterology, 124(4), A591-A592. doi:10.1016/s0016-5085(03)82997-9
• Kao, J. Y., Zavros, Y., & Merchant, J. L. (2003). Helicobacter pylori induces dendritic cell maturation and Th1 cytokine production. Gastroenterology, 124(4), A592. doi:10.1016/s0016-5085(03)83001-9
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  whether ,SST exerts an effect on an antigen p~vsenting cell (e.g., DCs).Mefhods: Bone marrow cells t?om 8-wk old C57B116 mine were cultured in complete media supplemented with IL-4/GM-C,SF tbr 7 days.Final cultures contained 90% DCs after enrichment was achieved by metrizamide gradient centrffi.~garionDCs were pretreated with PB,5 or S,ST (10 ~ M) for 36 h then co-cultured with E. Cull-derived LP,5 (1 b~}/ml) tor 24 h.Dual-color FACS analysis (Coulter Cytometer) was performed in triphcate using FITC-coNugated MHC II as a DC marker and PE-conjugated anti-CD40, anti-lL-12, or II_-i0.P values are determined by Chisquare analysis.Results: We found S,ST pretreatment reduced the percent of CD40 positive DCs (PBS = 14.9%~PB,5 + LPS = 32.1%, and SST + 12,5 = 15.1%,P
• Law, D. J., & Merchant, J. L. (2003). Colitis generated in mice expressing an N-terminal truncated version of transcription factor ZBP-89. Gastroenterology, 124(4), A26. doi:10.1016/s0016-5085(03)80129-4
• Merchant, J. (2003). A model for integrative study of human gastric acid secretion. Journal of Applied Physiology.
• Merchant, J. (2003). Acinetobacter lwoffii infection and gastritis. Microbes and Infection.
• Merchant, J. (2003). Mutation of p53 in recurrent hepatocellular carcinoma and its association with the expression of ZBP-89. American Journal of Pathology.
• Merchant, J. (2003). Transcription factor ZBP-89 is required for STAT1 constitutive expression. Nucleic Acids Research.
• Merchant, J. (2003). Treatment of Helicobacter gastritis with IL-4 requires somatostatin. Proceedings of the National Academy of Sciences of the United States of America.
• Merchant, J. (2003). ZBP-89 mediates butyrate regulation of gene expression. Journal of Nutrition.
• Tucker, T. P., & Merchant, J. L. (2003). Regulation of the gastrin promoter by AP1 at Sp1 DNA elements. Gastroenterology, 124(4), A9. doi:10.1016/s0016-5085(03)80045-8
• Wang, L., Yao, H., Lu, Y., Song, I., Zavros, Y., Owyang, C., & Merchant, J. L. (2003). Interferon-γ down regulates nNOS expression and causes defective gastric relaxation in helicobacter pylori-infected mice: Mediation by somatostatin. Gastroenterology, 124(4), A119. doi:10.1016/s0016-5085(03)80585-1
• Merchant, J. (2002). Gastritis and hypergastrinemia due to Acinetobacter lwoffii in mice. Infection and Immunity.
• Merchant, J. (2002). Genetic or chemical hypochlorhydria is associated with inflammation that modulates parietal and G-cell populations in mice. Gastroenterology.
• Merchant, J. (2002). Hypergastrinemia in response to gastric inflammation suppresses somatostatin. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2002). Regulation of epithelial cell growth by ZBP-89: Potential relevance in pancreatic cancer. International Journal of Gastrointestinal Cancer.
• Bai, L., & Merchant, J. L. (2001). Transcription factor ZBP-89 regulates p53 transcriptional activity by interacting with DNA binding and C-terminal domains. Gastroenterology, 120(5), A293. doi:10.1016/s0016-5085(08)81454-0
• Merchant, J. (2001). Retinoic acid (RA) receptor transcriptional activation correlates with inhibition of 12-O-tetradecanoylphorbol-13-acetate-induced ornithine decarboxylase (ODC) activity by retinoids: A potential role for trans-RA-induced ZBP-89 in ODC inhibition. International Journal of Cancer.
• Merchant, J. (2001). TNF-α and interleukin 1 activate gastrin gene expression via MAPK- and PKC-dependent mechanisms. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (2001). VacA pores as portable portals for urea. Journal of Clinical Investigation.
• Merchant, J. (2001). ZBP-89 promotes growth arrest through stabilization of p53. Molecular and Cellular Biology.
• Merchant, J. (2001). ZBP-89, Sp1, and Nuclear Factor-κB Regulate Epithelial Neutrophil-activating Peptide-78 Gene Expression in Caco-2 Human Colonic Epithelial Cells. Journal of Biological Chemistry.
• Zavros, Y., & Merchant, J. L. (2001). Regulation of somatostatin and gastrin by interferon-γ in the mouse gastric mucosa. Gastroenterology, 120(5), A727. doi:10.1016/s0016-5085(08)83621-9
• Bai, L., & Merchant, J. L. (2000). Adenoviral protein E1A prevents potentiatiation of butyrate-activated p21WAFL by ZBP-89 through direct binding. Gastroenterology, 118(4), A864. doi:10.1016/s0016-5085(00)85597-3
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  The peroxisome proliferator-activated receptor "I (PPAR'Y) is highly expressed in colonic mucosa and exerts in vitro an anti-inflammatory effect (I).PPAR'Y expression is decreased in the colon of patients with ulcerative colitis (2) but the functions of this receptor in the colon mucosa remain unknown.Aim: To investigate the therapeutic role of a PPAR'Y agonist administered in a preventive or treatment modes during TNBS-induced colitis in mice.Methods: Twelve groups of male Balb/c mice (416 per group) received an intrarectal administration of ethanol 50% or saline (Controls) or TNBS (150mg/kg in 50% ethanol).PPAR'Y agonist (BRL, 20 mg/kglday, Ligand Pharmaceuticals) was given once daily by oral gavage respectively 2 days before colitis induction or just after TNBS-administration.An acute or chronic inflammation was observed respectively 2 or 5 days after TNBS-administration.The distal colon was removed to evaluate macroscopic (Wallace score) and histologic inflammation (Ameho score), myeloperoxydase (MPO)(Western blot, optical density (OD)/50ng protein), TNFa and IL-lf3 mRNA concentrations (competitive PCR, molecules of cytokineIl0-6/Lg RNA), and the NFKB, p38 and JNK activities (arbitrary units).Results: TNBS administration induced a marked macroscopic and histologic inflammation (respectively 8:t2 and 5:t 1) associated with high concentrations of MPO (34:t 16), TNFa (390:t394 molecules), IL-lf3 mRNA (29:t31 molecules), and increased activities of NFKB (108:t4), p38 (15:t0.7)and JNK (9:±:0.3).BRL given prior or after induction of inflammation reduced significantly and similarly the macroscopic (4 :t 1) and histologic (1.5 :t 1) scores of inflammation and normalised MPO (l :t 5), TNFa (29:t31), IL-lf3 (4:t3) levels and NFKB (55:t5), p38 (l0:t2) and JNK (6:t 1) activities (p
• Bai, L., & Merchant, J. L. (2000). Butyrate-dependent activation of p21WAF1 is potentiated by ZBP-89. Gastroenterology, 118(4), A865. doi:10.1016/s0016-5085(00)85600-0
• Merchant, J. (2000). An OmpA-like protein from Acinetobacter spp. stimulates gastrin and interleukin-8 promoters. Infection and Immunity.
• Merchant, J. (2000). EGF receptor activation of the human gastrin gene: A tale of two zinc finger transcription factor families. Keio Journal of Medicine.
• Merchant, J. (2000). EGF stimulates gastrin promoter through activation of Sp1 kinase activity. American Journal of Physiology - Cell Physiology.
• Merchant, J. (2000). The zinc finger repressor, ZBP-89, binds to the silencer element of the human vimentin gene and complexes with the transcriptional activator, Sp1. Journal of Biological Chemistry.
• Merchant, J. (2000). Transcription factor ZBP-89 cooperates with histone acetyltransferase p300 during butyrate activation of p21(waf1) transcription in human cells. Journal of Biological Chemistry.
• Merchant, J. (2000). Use of flow cytometry to quantify mouse gastric epithelial cell populations. Digestive Diseases and Sciences.
• Merchant, J. L., Zavros, Y., & Rieder, G. (2000). Atrophic gastritis and hypergastrinemia due to colonization by acinetobacter in mice. Regulatory Peptides, 94(1-3), 5. doi:10.1016/s0167-0115(00)80011-7
• Merchant, J. L., Zavros, Y., Ferguson, A. W., & Samuelson, L. C. (2000). Antibiotics reverse atrophic gastritis in gastrin deficient mice. Regulatory Peptides, 94(1-3), 4. doi:10.1016/s0167-0115(00)80008-7
• Merchant, J. (1999). Sp1 phosphorylation by Erk 2 stimulates DNA binding. Biochemical and Biophysical Research Communications.
• Merchant, J. (1999). ZBP-99 defines a conserved family of transcription factors and regulates ornithine decarboxylase gene expression. Biochemical and Biophysical Research Communications.
• Walsh, J., Merchant, J. L., & Wang, T. C. (1999). Abstracts of the conference on gastrin. Digestion, 60(6), 591-619. doi:10.1159/000007714
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  Meeting Reports/Abstracts| October 25 1999 Abstracts of the Conference on Gastrin Subject Area: Gastroenterology Juanita> Merchant; Juanita> Merchant Search for other works by this author on: This Site PubMed Google Scholar John Walsh; John Walsh Search for other works by this author on: This Site PubMed Google Scholar Timothy Wang Timothy Wang Search for other works by this author on: This Site PubMed Google Scholar Digestion (1999) 60 (6): 591–619. https://doi.org/10.1159/000007714 Content Tools Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Juanita> Merchant, John Walsh, Timothy Wang; Abstracts of the Conference on Gastrin. Digestion 1 December 1999; 60 (6): 591–619. https://doi.org/10.1159/000007714 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsDigestion Search Advanced Search Article PDF first page preview Close Modal Journal Section: Further Section This content is only available via PDF. Copyright / Drug Dosage / DisclaimerCopyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements. 1999 You do not currently have access to this content.
• Arii, K., & Merchant, J. L. (1998). Correlation of Sp1 and ZBP-89 protein expression with gastric cancer subtype. Gastroenterology, 114, A558-A559. doi:10.1016/s0016-5085(98)82271-3
• Merchant, J. (1998). The human ZBP-89 homolog, located at chromosome 3q21, represses gastrin gene expression. Mammalian Genome.
• Merchant, J. (1998). Transcription factor ZBP-89 regulates the activity of the ornithine decarboxylase promoter. Journal of Biological Chemistry.
• Merchant, J. L., Tarle, S. A., Du, M., Ford, M., & Todisco, A. (1998). The ras-Erk kinase signal transduction pathway stimulates the gastrin promoter through the GC-rich gERE element. Gastroenterology, 114, A1164. doi:10.1016/s0016-5085(98)84733-1
• Merchant, J. (1997). EGF receptor activation stimulates endogenous gastrin gene expression in canine G cells and human gastric cell cultures. Journal of Clinical Investigation.
• Merchant, J. (1997). Epidermal growth factor and okadaic acid stimulate Sp1 proteolysis. Journal of Biological Chemistry.
• Merchant, J. (1997). Gastrin regulates the human histidine decarboxylase promoter through an AP-1-dependent mechanism. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (1997). Overexpression of ZBP-89, a zinc finger DNA binding protein, in gastric cancer. Biochemical and Biophysical Research Communications.
• Merchant, J. (1997). RAP1-like binding activity in islet cells corresponds to members of the Sp1 family of transcription factors. FEBS Letters.
• Merchant, J. (1997). Transient transcriptional activation of gastrin during sodium butyrate- induced differentiation of islet cells. Regulatory Peptides.
• Merchant, J. (1997). ZBP-89, a Kruppel-type zinc finger protein, inhibits cell proliferation. Biochemical and Biophysical Research Communications.
• Marks, P., Iyer, G., Gui, Y., & Merchant, J. L. (1996). Fos is required for EGF stimulation of the gastrin promoter. American Journal of Physiology - Gastrointestinal and Liver Physiology, 271(Issue 6). doi:10.1152/ajpgi.1996.271.6.g942
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  Gastrin gene expression is regulated by developmental cues, pH, and inflammation. These processes are mediated by various extracellular ligands, e.g., growth factors, cytokines, and neuropeptides that also stimulate c-fos gene expression. Therefore, to determine whether Fos is required for stimulation of the gastrin promoter, a c-fos sense expression vector was coexpressed with a gastrin reporter construct in a GH4 rat pituitary cell line. We found that epidermal growth factor (EGF) and tumor necrosis factor- α (TNF-α) transiently stimulate an increase in Fos protein that precedes stimulation of the gastrin promoter. However, the induction mediated by TNF- α was weaker than that mediated by EGF, indicating minimal overlap of the signaling pathways activated by EGF and TNF-α. Accordingly, overexpression of c-fos mRNA facilitated primarily EGF rather than TNF-α induction of the gastrin promoter. Expression of the c-fos gene in the absence of ligand did not stimulate the gastrin promoter. Thus c-fos gene expression is required but is not sufficient for induction of the gastrin promoter by EGF.
• Merchant, J. (1996). Fos is required for EGF stimulation of the gastrin promoter. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Merchant, J. (1996). ZBP-89, a kruppel-like zinc finger protein, inhibits epidermal growth factor induction of the gastrin promoter. Molecular and Cellular Biology.
• Merchant, J. (1995). Epidermal growth factor stimulation of the human gastrin promoter requires Sp1. Journal of Biological Chemistry.
• Merchant, J. (1995). Sp1 Affinity for GC-Rich Elements Correlates with Ornithine Decarboxylase Promoter Activity. Biochemical and Biophysical Research Communications.
• Merchant, J. (1995). cAMP regulates gastrin gene expression. American Journal of Physiology - Gastrointestinal and Liver Physiology.
• Bachwich, D., Merchant, J., & Brand, S. J. (1992). Identification of a cis-regulatory element mediating somatostatin inhibition of epidermal growth factor-stimulated gastrin gene transcription. Molecular Endocrinology, 6(Issue 8).
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  Antrat gastrin secretion and gene expression is inhibited by the paracrine release of somatostatin from antral D cells. Transforming growth factor-α and epidermal growth factor (EGF) stimulate gastrin reporter gene constructs when transfected into pituitary GH4 cells. Somatostatin inhibits EGF stimulation of gastrin gene expression, which is in part mediated at the level of transcriptional regulation as somatostatin inhibits EGF stimulation of gastrin reporter gene constructs. Somatostatin inhibition was abolished by pertussis toxin, indicating somatostatin inhibits transcription through the inhibitory G protein Gi. Somatostatin inhibition was unaffected by vanadate and okadaic acid, implying this inhibitory pathway is mediated neither through phosphotyrosine phosphatases nor serine/threonine phosphatases, respectively. Gastrin reporter genes containing 82 base pairs of the 5′-flanking DNA were sufficient to confer both EGF responsiveness and inhibition by somatostatin in GH4 cells. However, transcription of a gastrin reporter gene construct containing only the EGF response element (GGGGCGGGGTGGGGGG), located at -68 to -53, was stimulated by EGF but was not inhibited by somatostatin. Thus, somatostatin inhibits EGF-stimulated gastrin gene transcription by a mechanism other than by interfering with cell signals elicited by the EGF receptor. Since the 82 GASCAT is inhibited by somatostatin, this result also implies that sequences adjacent to the EGF response element contain a cis-regulatory element mediating transcriptional inhibition by somatostatin. This cis-element was located using gastrin reporter genes comprising sequential segments of the human gastrin promoter sequence from the transcriptional start site to -82 in the 5′-flanking DNA. Gastrin oligonucleotide constructs lacking the D oligonucleotide (gatcCATATGGCAGGGTA), located at -82 to -69 in the 5′-flanking DNA, were not inhibited by somatostatin, indicating that a somatostatin inhibitory cis-element is located between -82 and -69 in the 5′-flanking DNA of the human gastrin promoter.
• Merchant, J. (1992). Identification of a cis-regulatory element mediating somatostatin inhibition of epidermal growth factor-stimulated gastrin gene transcription. Molecular Endocrinology.
• Merchant, J. L., Valle, J. D., & Wilson, E. J. (1992). EGF regulates gastrin gene expression in canine primary G cells. Regulatory Peptides, 40(2), 208. doi:10.1016/0167-0115(92)90333-p
• Merchant, J. (1991). A GC-rich element confers epidermal growth factor responsiveness to transcription from the gastrin promoter. Molecular and Cellular Biology.
• Merchant, J. (1991). Stimulation of gastrin gene transcription by epidermal growth factor/TGFα and inhibition by somatostatin-feedforward and feedback controls on gastrin synthesis to prevent mucosal ulceration by gastrin acid secretion. Fernstrom Foundation Series.
• Merchant, J. (1989). Regulation of the gastrin promoter by epidermal growth factor and neuropeptides. Proceedings of the National Academy of Sciences of the United States of America.
• Merchant, J. (1987). Characterization and use of polyclonal antibody to Na⁺, K⁺‐ATPase: Immunocytochemical localization in salt glands of the duck. Cell Biochemistry and Function.
• Merchant, J. (1985). Correlation of Na+,K+-ATPase content and plasma membrane surface area in adapted and de-adapted salt glands of ducklings.. Journal of cell science.
• Merchant, J. (1977). 3-Hydroxy-3-methylglutaryl coenzyme A reductase in isolated villous and crypt cells of the rat ileum. Journal of Lipid Research.

Proceedings Publications

• Knapp, T., Duan, S., Alfonso-Garcia, A., Merchant, J. L., & Sawyer, T. W. (2024). Validation of label-free optical imaging markers of pancreatic cancer using spatial transcriptomics. In 2024 Label-free Biomedical Imaging and Sensing, LBIS 2024, 12854.
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  Label-free biomedical imaging represents a range of powerful technologies used to visualize natural sources of biological contrast. Label-free techniques such as autofluorescence and fluorescence lifetime imaging measure contrast produced by various cellular products and provide high sensitivity for detecting tissue changes that occur with disease onset. However, a major limitation of these modalities, and many label-free modalities broadly, is the lack of robust validation methods that confirm signal specificity. Moreover, existing approaches are limited to assessing correlations and fail to provide mechanistic information into pathological events. Spatially resolved gene sequencing methods (e.g., spatial transcriptomics) are a powerful tool to gain detailed biological insight into tissue properties by creating 2-D maps of variations in gene expression that influence tissue properties. Thus, these techniques represent an avenue for validation of label-free imaging markers through the examination of how label-free image features correspond to gene expression. Toward this aim, we performed autofluorescence and fluorescence lifetime imaging on tissue specimens from four patients presenting with pancreatic neuroendocrine tumors. We then performed spatial transcriptome sequencing on serial tissue sections to measure transcriptome-wide signatures. We assessed imaging biomarkers related to cellular metabolism, vasculature, and extracellular matrix properties. After registering the label-free images to the transcriptomic signatures, we performed k-means clustering, and assessed the correlation between imaging markers and differentially expressed genes associated with tissue properties of interest. Specifically, we aimed to examine correlations between gene expression and established optical biomarkers (e.g., optical redox ratio), along with identifying other potential connections between label-free optics and cellular genetics. The results show that spatial transcriptomics can be used as an effective validation tool for label-free imaging markers, while simultaneously providing additional biological insight to improve the specificity of imaging studies.
• Kropatsch, M., Daigle, N., Duan, S., Sontz, R., Merchant, J. L., & Sawyer, T. W. (2024). Evaluating the impact of freeze-thaw protocols on tissue microstructural imaging features measured using optical coherence tomography. In 2024 Label-free Biomedical Imaging and Sensing, LBIS 2024, 12854.
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  Cryopreservation is routine in biomedical research and clinical practice for various purposes, including sample transportation, RNA preservation, and long-term storage. However, freezing poses risks of tissue damage due to ice crystal formation and cell lysis. The effects of tissue freezing and thawing on microstructural image features are not fully understood, and determining a freezing protocol that best preserves tissue integrity is essential for maximizing the transferability of imaging studies using previously frozen tissues. This study investigates the impact of freeze-thaw protocols on tissue microstructure using optical coherence tomography (OCT), an imaging technique that provides detailed 3D images of biological structures. Tissue specimens from three organs - lung, liver, and duodenum - were collected from six mice and imaged before and after freeze-thawing using different protocols. We tested protocols including slow freezing to -20 °C, slow freezing to -80 °C, and liquid nitrogen submersion. We examined immersion in both phosphate buffered saline and routine cryopreservation compounds for all methods. Using images from each specimen before and after freeze-thawing, differences in structural features were analyzed qualitatively and by using texture analysis. Texture features were extracted from OCT images using Haralick's method, and statistical analysis was performed to compare the different protocols and tissue types. Results show that flash freezing methods and the use of cryopreservation compounds cause fewer alterations in tissue microstructure compared to slow freezing. This study provides insight into the effects of common freezing protocols on tissue integrity, which may inform the optimization of tissue preservation techniques across many disciplines.
• Stilson, E. H., Lima, N., Setiadi, J., Sontz, R., Duan, S., Merchant, J., & Sawyer, T. (2024). Fixative Induced Effects in Labeled and Unlabeled Fluorescence: Implications for Biomedical Imaging Studies. In Multiscale Imaging and Spectroscopy V 2024, 12827.
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  Paraformaldehyde (PFA) is one of the most common fixatives in biological and biomedical research. It is used to preserve tissue or cell morphology while preventing contamination by crosslinking proteins and other biological molecules. Although fixation is required for histology, it has been documented that chemical fixation can cause alterations in the fluorescence properties of exogenous and endogenous fluorophores, which are valuable markers for understanding biological processes, ultimately reducing the accuracy and reliability of quantitative fluorescence measurements. Therefore, there is a need for understanding the behavior of tissue fluorescence during PFA fixation. Multispectral fluorescence imaging (MFSI) is an imaging technique used in biological and biomedical research to visualize and quantify the fluorescence properties of tissue over several wavelength bands, enabling measurement of several fluorophores simultaneously. To evaluate the effects of PFA on tissue fluorescence, we imaged brain tissue samples using MSFI from two cohorts of mice: the SOX10 Cre; R26R-Brainbow 2.1/Confetti mice (expressing four exogenous fluorophores), and wild type Cre-negative controls. Specimens from each were immersed in 10 ml of PFA or phosphate buffer saline (PBS) as a control. The fluorescence intensity was captured using MFSI every 15 minutes over three hours. Analysis was performed on the resulting images to produce quantitative metrics of the resulting fluorescence signal. The results show that exogenous fluorophores are dramatically quenched within the first half hour when fixed in PFA, whereas endogenous fluorescence increased slightly in the same time period. These results are valuable to understand how fixation can influence fluorescence properties and can inform optimal fixation protocols.
• Daigle, N., Knapp, T., Duan, S., Jones, D. W., Azhdarinia, A., Ghosh, S. C., AghaAmiri, S., Ikoma, N., Estrella, J., Schnermann, M. J., Merchant, J. L., & Sawyer, T. W. (2023). Combined multiphoton microscopy and somatostatin receptor type 2 imaging of pancreatic neuroendocrine tumors. In Multimodal Biomedical Imaging XVIII 2023, 12371.
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  Pancreatic neuroendocrine tumors (PNETs) are a rare but increasingly more prevalent cancer with heterogeneous clinical and pathological presentation. Surgery is the preferred treatment for all hormone-expressing PNETs and any PNET greater than 2 cm, but difficulties arise when tumors are multifocal, metastatic, or small in size due to lack of effective surgical localization. Existing techniques such as intraoperative ultrasound provide poor contrast and resolution, resulting in low sensitivity for such tumors. Somatostatin receptor type 2 (SSTR2) is commonly overexpressed in PNETs and presents an avenue for targeted tumor localization. SSTR2 is often used for pre-operative imaging and therapeutic treatment, with recent studies demonstrating that somatostatin receptor imaging (SRI) can be applied in radioguided surgery to aid in removal of metastatic lymph nodes and achieving negative surgical margins. However not all PNETs express SSTR2, indicating labeled SRI could benefit from using a supplemental label-free technique such as multiphoton microscopy (MPM), which has proven useful in improving the accuracy of diagnosing more common exocrine pancreatic cancers. Our work tests the suitability of combined SRI and MPM for localizing PNETs by imaging and comparing samples of PNETs and normal pancreatic tissue. Specimens were labeled with a novel SSTR2-targeted contrast agent and imaged using fluorescence microscopy, and subsequently imaged using MPM to collect four autofluorescent channels and second harmonic generation. Our results show that a combination of both SRI and MPM provides enhanced contrast and sensitivity for localizing diseased tissue, suggesting that this approach could be a valuable clinical tool for surgical localization and treatment of PNETs.
• Setiadi, J. C., Bonaventura, J., Knapp, T. G., Duan, S., Merchant, J. L., & Sawyer, T. W. (2023). Mueller Matrix polarization imaging of gastrinoma shows promise for tumor localization. In Label-free Biomedical Imaging and Sensing (LBIS) 2023, 12391.
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  Gastrinomas are gastrin-producing neuroendocrine tumors (NETs) located in the gastroenteropancreatic system. Gastrinomas are often small, multifocal, and found at late stages. Their unpredictable behavior and metastatic potential make it extremely challenging to develop therapeutic strategies. Surgery is the only potentially curative treatment for gastrinoma, but current tumor localization techniques such as intraoperative ultrasound and manual palpitation have poor sensitivity for small tumors, resulting in higher rates of recurrence and metastasis. Therefore, there is a strong clinical need for developing advanced intraoperative imaging technologies for tumor localization in treating gastrinoma. Polarized light imaging (PLI) is a promising method for label-free tissue characterization due to its sensitivity to micro and nanoscale structures, which are often influenced with the onset of cancer, but no works have yet investigated the application of PLI for gastrinoma localization. To assess the suitability of PLI for gastrinoma localization, we imaged 11 formalin-fixed paraffin embedded (FFPE) specimens of gastrinoma using a five-wavelength Mueller Matrix Polarization Microscope. The Lu-Chipman decomposition was applied to spatial maps of the sixteen Mueller matrix parameters. Values for depolarization, diattenuation, and retardance were compared for regions of interest corresponding to tumor and adjacent tissues. There was significant difference between the average depolarization of the Brunner’s gland and tumors when imaged with light at 442, 543, and 632nm (p
• Duan, S., Sontz, R., Merchant, J. L., & Sawyer, T. W. (2022). Measuring variations in optical imaging markers in a glial cell-directed mouse model of human MEN1 syndrome. In Label-free Biomedical Imaging and Sensing (LBIS) 2022, 11972.
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  Gastrointestinal neuroendocrine tumors (GI-NETs) including gastric carcinoids and duodenal neuroendocrine tumors (DNETs), represent a growing class of cancer.1 There is a strong need for intraoperative localization to facilitate diagnosis and treatment of DNETs, particularly those related to the hereditary MEN1 syndrome. However, these demands are precluded by a lack of in vivo model systems that accurately recapitulate disease heterogeneity and progression. Optical imaging markers are commonly used diagnostically to probe early tissue changes that occur with the onset of cancer. Promising techniques include autofluorescence imaging (AFI), which probes intrinsic biochemistry and metabolic markers, and optical coherence tomography (OCT), which provides a robust microstructural reference. Both have demonstrated widespread promise for non-invasive disease screening, making them potential candidates for localization of DNETs. Here we apply AFI and OCT to a mouse model of human MEN1 syndrome to identify unique optical markers associated with neuroendocrine cell reprogramming. Using Cre-lox technology, we generated a glial cell-directed Men1 knockout mouse model that exhibits enhanced neuroendocrine cell differentiation in the stomach and duodenum. We measured variations in optical imaging markers using AFI and OCT images of transgenic and wild type mice. The transgenic lines exhibit significant fluctuations in optical imaging markers compared to wild type mice, both in the scope of AFI and OCT (p
• Knapp, T., Lima, N., Duan, S., Merchant, J. L., & Sawyer, T. W. (2022). Evaluation of tile artifact correction methods for multiphoton microscopy mosaics of whole-slide tissue sections. In Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXIX 2022, 11966.
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  Multi-photon microscopy (MPM) is a useful biomedical imaging tool due, in part, to its capabilities of probing tissue biomarkers at high resolution and with depth-resolved capabilities. Automated MPM tile scanning allows for whole-slide image acquisition but suffers from tile-stitching artifacts that prevent accurate quantitative data analysis. We have investigated a variety of post-processing artifact correction methods using ImageJ macros and custom Python/ MATLAB code and present a quantitative and qualitative comparison of these methods using whole-slide MPM autofluorescence images of human duodenal tissue. Image quality is assessed via evaluation of artifact removal compared to the calculated mean square error (MSE), peak signal-to-noise ratio (PSNR), and structural similarity index (SSIM) of the processed image and its raw counterpart. Consideration of both quantitative and qualitative results suggest a combination of flat-field based correction and frequency filtering processing steps provide improved artifact correction when compared to each method used independently to correct for tiling artifacts of tile-scan MPM images.
• Slomka, B., Duan, S., Sontz, R., Merchant, J. L., & Sawyer, T. W. (2022). Multi-band fluorescence imaging and cell collection device for in vivo tumor characterization and growth assessment in xenograft mouse models. In Imaging, Manipulation, and Analysis of Biomolecules, Cells, and Tissues XX 2022, 11964.
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  Mouse models are essential tools for understanding cancer growth and accelerating the development of therapeutic and diagnostic technologies. Xenografts, generated by implanting tumor cells directly into mice through injection, are frequently used to study cancer biology and therapeutics. In these models, assessment of tumor growth and development is necessary to support the study of disease progression and model validation. Unfortunately, such measurements often require sacrificing the animal to create organ explants or tissue cultures, resulting in increased animal use and hampering longitudinal measurements of individual tumors. A tool enabling in vivo tumor monitoring for xenograft models could improve the efficiency of these animal models and provide more robust growth measurements through true longitudinal measurement. One method of optical tumor assessment involves tagging biomolecules of interest with fluorescent species to enable detection with minimally invasive fluorescence imaging, implemented endoscopically or laparoscopically. However, utilizing fluorescence imaging in vivo in murine models poses challenges due to both tortuous anatomy and small gastrointestinal lumen caliber. This work reports a miniature fluorescence imaging probe equipped with a multiband filter and biopsy device to image and sample fluorescently-tagged, xenografted tumors as they develop in mouse models. We present the design and characterization of the device and report measurements of the modulation transfer function and ex vivo imaging performance, demonstrating its promise as a valuable research tool to advance cancer research in xenograft models, enabling the development of imaging biomarkers for cancer detection in a clinical setting without the need for exogenous contrast.